Mutant cell with deleted or disrupted genes encoding protease

ABSTRACT

This disclosure relates to mutant cells with deleted or disrupted genes encoding protease(s).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a 35 U.S.C. 371 national application ofPCT/EP2008/063102 filed Sep. 30, 2008, which claims priority or thebenefit under 35 U.S.C. 119 of European application no. 07117588 filedOct. 1, 2007 and U.S. provisional application No. 60/977,235 filed Oct.3, 2007, the contents of which are fully incorporated herein byreference.

REFERENCE TO SEQUENCE LISTING

This application contains a Sequence Listing in computer readable form.The computer readable form is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to isolated polypeptides having proteaseactivity and isolated polynucleotides encoding the polypeptides. Theinvention also relates to nucleic acid constructs, vectors, and hostcells comprising the polynucleotides as well as methods for producingand using the polypeptides.

BACKGROUND OF THE INVENTION

It is an object of the present invention to provide polypeptides havingprotease activity and polynucleotides encoding the polypeptides.

In the detergent industry enzymes have for more than 30 years beenimplemented in washing formulations. Enzymes used in such formulationscomprise proteases, lipases, amylases, cellulases, mannosidases as wellas other enzymes or mixtures thereof. Commercially most importantenzymes are proteases.

WO 89/06270 (Novozymes A/S) discloses a detergent composition comprisinga protease with a narrow substrate specificity, namely a trypsin-likeprotease capable of cleaving peptide bonds at C-terminal side of lysineor arginine.

Further WO 94/25583 discloses the cloning of a DNA sequence encoding aFusarium trypsin-like protease and obtaining expression of an activetrypsin-like protease from said DNA-sequence.

However, even though a number of useful proteases and protease variantshave been described, there is still a need for further improvement ofproteases or protease variants for a number of industrial uses.

In particular, the problem of maintaining high activity in the presenceof other components of typical detergent compositions tends to reducethe performance of proteases.

Therefore, an object of the present invention is to provide newproteases, which are suitable for use in detergents for the use in forexample laundry and/or cleaning of hard surfaces.

Fungi, and especially filamentous fungi, are widely used commerciallybecause of their ability to secrete remarkably high levels of proteins.

Among the filamentous fungi species belonging to the genus Aspergillushave a long history of commercial use for the production of endogenousand heterologous proteins.

One disadvantage with most microorganisms used for the production ofproteins is the inherent production of proteases which may subject aprotein product of interest to degradation due to proteolysis.

Various ways of avoiding this have been envisaged. Among other solutionsit has been suggested to delete or disrupt the genes encoding thevarious proteases.

WO 2006/110677 discloses recombinant fungal host cell belonging to thespecies Aspergilus niger, wherein the chromosomal genes derA, derB,htmA, mnn9, mnn10, ochA, pepAa, pepAb, pepAc, pepAd, pepF andcombination had been inactivated in order to reduce degradation ofheterologously produced proteins.

Unfortunately, some fungi produce a high number of different proteases.

A need is therefore persisting for strains of filamentous fungiexhibiting no or very low levels of protease production.

SUMMARY OF THE INVENTION

The present invention relates to an isolated protease having an aminoacid sequence which has at least 95% identity with amino acids 2 to 148of SEQ ID NO: 5.

The present invention also relates to methods for producing suchpolypeptides having protease activity comprising (a) cultivating arecombinant host cell comprising a nucleic acid construct comprising apolynucleotide encoding the polypeptide under conditions conducive forproduction of the polypeptide; and (b) recovering the polypeptide.

The present invention also relates to a cleaning or detergentcomposition, preferably a laundry or dish wash composition, comprisingthe protease according to the invention.

Further aspects of the present invention relate to use of the proteasesaccording to the invention in a cleaning or detergent composition; amethod for cleaning or washing a hard surface or laundry comprisingcontacting the hard surface or the laundry with the composition of theinvention

The present invention also relates to fungi, modified so that theexpression of the protease of the invention have been reduced orcompletely abolished compared to the corresponding not modified fungi.Preferably the modification has been performed using recombinant DNAtechnology.

Thus the invention furthermore relates to methods for producing suchfungi, obtained by deletion of at least a part of polynucleotidesencoding polypeptides having protease activity, selected from the groupconsisting of:

(a) a polynucleotide encoding a polypeptide having an amino acidsequence which has at least 60%, such as at least 65%, such as at least70%, such as at least 75%, such as at least 80%, such as at least, 85%,such as at least, 90%, such as at least, 95%, such as at least 95%, suchas at least 96%, such as at least 97%, such as at least 98%, such as atleast 99%, such as at least 99.5% identity with amino acids 2 to 148 ofSEQ ID NO: 5;

(b) a polynucleotide which hybridizes under at least medium stringencyconditions with nucleotides 1 to 515 of SEQ ID NO: 4, or a complementarystrand thereof.

This may be obtained through a method comprising:

-   -   i) cloning of a polynucleotide encoding a polypeptide having        protease activity, selected from the group consisting of:        -   (a) a polynucleotide encoding a polypeptide having an amino            acid sequence which has at least 60%, such as at least 65%,            such as at least 70%, such as at least 75%, such as at least            80%, such as at least, 85%, such as at least, 90%, such as            at least, 95%, such as at least 95%, such as at least 96%,            such as at least 97%, such as at least 98%, such as at least            99%, such as at least 99.5% identity with amino acids 2 to            148 of SEQ ID NO: 5;        -   (b) a polynucleotide which hybridizes under at least medium            stringency conditions with nucleotides 1 to 515 of SEQ ID            NO: 4, or a complementary strand thereof;    -    from a fungus of interest,    -   ii) producing DNA constructs comprising the polynucleotide        cloned in i) wherein an internal part has been substituted,        deleted, or extra DNA has been inserted,    -   iii) transforming said fungus with the constructs, and    -   iv) isolating transformants which express an reduced amount of        the protease of the invention, compared to the amount expressed        by the not modified fungus.

Further, the invention also related to methods for producing fungi wherethe expression of the protease of the invention has been reducedcompared to the unmodified parent fungi, where the expression has beenreduced using the well-known anti-sense technology, by constructing avector that upon introduction into said fungi gives rise to synthesis ofa RNA-molecule complementary the mRNA transcribed from polynucleotidesencoding polypeptides having protease activity, selected from the groupconsisting of:

(a) a polynucleotide encoding a polypeptide having an amino acidsequence which has at least 60%, such as at least 65%, such as at least70%, such as at least 75%, such as at least 80%, such as at least, 85%,such as at least, 90%, such as at least, 95%, such as at least 95%, suchas at least 96%, such as at least 97%, such as at least 98%, such as atleast 99%, such as at least 99.5% identity with amino acids 2 to 148 ofSEQ ID NO: 5;

(b) a polynucleotide which hybridizes under at least medium stringencyconditions with nucleotides 1 to 515 of SEQ ID NO: 4, or a complementarystrand thereto.

The invention furthermore relates to DNA constructs intended for use inthe above mentioned methods.

Furthermore the invention relates to methods of producing a desiredprotein or gene product, especially secreted proteins, whereby a fungalhost modified and optionally transformed with a DNA construct comprisingat least a DNA sequence coding for the protein or gene product ofinterest, is cultivated in a suitable growth medium at appropriateconditions and the desired gene product is recovered and purified.

When working with the invention it was surprisingly found that the fungiof the invention produces such secreted proteins in a much improvedyield. In particular it has been found that the polypeptide of theinvention appears to be responsible for cleaving a CBM (carbohydratebinding module) from a polypeptide comprising a catalytic part and aCBM, and that host cells in which the expression of the polypeptide ofthe invention has been reduced gives rise to less cleaving of the CBMcompared with the same host cell but where the expression of thepolypeptide of the invention has not been reduced.

Thus another aspect of the invention relates to a method for producing aprotein product comprising a polypeptide comprising two or more domainsof which one domain is carbon hydrate binding module, wherein the methodcomprises the steps of,

-   -   a) fermentation of a cell having reduced expression of the        polypeptide according to any of the claims 1-2, which cell        produces said polypeptide comprising two or more domains, and    -   b) recovering the product.        In a further the invention also relates methods for producing        protein product essentially free of the protease activity of the        polypeptide according to the invention, such as a method        comprising the steps of,    -   a) fermentation of a cell expressing a polypeptide according to        any of the claims 1-8 as well as a protein product of interest,    -   b) adding agent capable of inhibiting protease activity of a        polypeptide according to the invention to the fermentation broth        before, during or after the fermentation has been completed, and    -   c) recovering product of interest from fermentation broth.        Or a method comprising the steps of    -   a) cultivating a cell under conditions permitting expression of        said protein product,    -   b) subjecting the culture to combined pH and temperature        treatment, and    -   c) recovering the product.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a SDS-PAGE gel showing the purified 19 kDa protease of theinvention, as described in Example 1.

FIG. 2 shows the genomic DNA sequence and the deduced amino acidsequence of an Aspergillus niger 19 kDa protease (SEQ ID NOs: 4 and 5,respectively).

FIG. 3 shows a gel permeation chromatography of an A. oryzae transformedwith an expression plasmid comprising the polynucleotide of theinvention.

FIG. 4 shows a SDS-PAGE gel loaded with selected fraction of the gelpermeation chromatography disclosed in FIG. 3.

FIG. 5 shows the pH profile of the protease having SEQ ID NO: 3

DEFINITIONS

Protease activity: The term “protease activity” is defined herein as aproteolytic activity which catalyzes the hydrolysis of the peptide bondconnecting two amino acids in a peptide. For purposes of the presentinvention, protease activity is determined according to the proceduredescribed by S. Ishiura, et al, FEBS Lett., 189, 119 (1985)]. One unitof protease activity is defined as 1.0 μmole of [aminomethylcoumarin]liberated from substrate Suc-LLVY-MCA (available at Peptide Inc. (Osaka,Japan)) per minute at 37° C., pH 6.7.

The polypeptides of the present invention have at least 20%, preferablyat least 40%, more preferably at least 50%, more preferably at least60%, more preferably at least 70%, more preferably at least 80%, evenmore preferably at least 90%, most preferably at least 95%, and evenmost preferably at least 100% of the protease activity of thepolypeptide consisting of the amino acid sequence shown as amino acids 2to 148 of SEQ ID NO: 5.

Isolated polypeptide: The term “isolated polypeptide” as used hereinrefers to a polypeptide that is removed from at least one component withwhich is natively associated. The term as used herein refer to apolypeptide which is at least 20% pure, preferably at least 40% pure,more preferably at least 60% pure, even more preferably at least 80%pure, most preferably at least 90% pure, and even most preferably atleast 95% pure, as determined by SDS-PAGE.

Substantially pure polypeptide: The term “substantially purepolypeptide” denotes herein a polypeptide preparation which contains atmost 10%, preferably at most 8%, more preferably at most 6%, morepreferably at most 5%, more preferably at most 4%, at most 3%, even morepreferably at most 2%, most preferably at most 1%, and even mostpreferably at most 0.5% by weight of other polypeptide material withwhich it is natively associated. It is, therefore, preferred that thesubstantially pure polypeptide is at least 92% pure, preferably at least94% pure, more preferably at least 95% pure, more preferably at least96% pure, more preferably at least 96% pure, more preferably at least97% pure, more preferably at least 98% pure, even more preferably atleast 99%, most preferably at least 99.5% pure, and even most preferably100% pure by weight of the total polypeptide material present in thepreparation.

The polypeptides of the present invention are preferably in asubstantially pure form. In particular, it is preferred that thepolypeptides are in “essentially pure form”, i.e., that the polypeptidepreparation is essentially free of other polypeptide material with whichit is natively associated. This can be accomplished, for example, bypreparing the polypeptide by means of well-known recombinant methods orby classical purification methods.

Herein, the term “substantially pure polypeptide” is synonymous with theterms “isolated polypeptide” and “polypeptide in isolated form.”

Identity: The relatedness between two amino acid sequences is describedby the parameter “identity”.

For purposes of the present invention, the alignment of two amino acidsequences is determined by using the Needle program from the EMBOSSpackage version 2.8.0. The Needle program implements the globalalignment algorithm described in Needleman, S. B. and Wunsch, C. D.(1970) J. Mol. Biol. 48, 443-453. The substitution matrix used isBLOSUM62, gap opening penalty is 10, and gap extension penalty is 0.5.

The degree of identity between an amino acid sequence of the presentinvention (“invention sequence”); e.g. amino acids 2-148 of SEQ ID NO: 5and a different amino acid sequence (“foreign sequence”) is calculatedas the number of exact matches in an alignment of the two sequences,divided by the length of the “invention sequence” or the length of the“foreign sequence”, whichever is the shortest. The result is expressedin percent identity.

An exact match occurs when the “invention sequence” and the “foreignsequence” have identical amino acid residues in the same positions ofthe overlap (in the alignment example below this is represented by “|”).The length of a sequence is the number of amino acid residues in thesequence (e.g. the length of SEQ ID NO: 5 is 148).

In the purely hypothetical alignment example below, the overlap is theamino acid sequence “HTWGER-NL” of Sequence 1; or the amino acidsequence “HGWGEDANL” of Sequence 2. In the example a gap is indicated bya “-”.

Hypothetical alignment example:

For purposes of the present invention, the degree of identity betweentwo nucleotide sequences is determined by the Wilbur-Lipman method(Wilbur and Lipman, 1983, Proceedings of the National Academy of ScienceUSA 80: 726-730) using the LASERGENE™ MEGALIGN™ software (DNASTAR, Inc.,Madison, Wis.) with an identity table and the following multiplealignment parameters: Gap penalty of 10 and gap length penalty of 10.Pairwise alignment parameters are Ktuple=3, gap penalty=3, andwindows=20.

In a particular embodiment, the percentage of identity of an amino acidsequence of a polypeptide with, or to, amino acids 2 to 148 of SEQ IDNO: 5 is determined by i) aligning the two amino acid sequences usingthe Needle program, with the BLOSUM62 substitution matrix, a gap openingpenalty of 10, and a gap extension penalty of 0.5; ii) counting thenumber of exact matches in the alignment; iii) dividing the number ofexact matches by the length of the shortest of the two amino acidsequences, and iv) converting the result of the division of iii) intopercentage.

Polypeptide Fragment: The term “polypeptide fragment” is defined hereinas a polypeptide having one or more amino acids deleted from the aminoand/or carboxyl terminus of SEQ ID NO: 5 or a homologous sequencethereof, wherein the fragment has protease activity.

Subsequence: The term “subsequence” is defined herein as a nucleotidesequence having one or more nucleotides deleted from the 5′ and/or 3′end of SEQ ID NO: 4 or a homologous sequence thereof, wherein thesubsequence encodes a polypeptide fragment having protease activity.Preferably, a subsequence contains at least 100 nucleotides, morepreferably at least 200 nucleotides, and most preferably at least 300nucleotides.

Allelic variant: The term “allelic variant” denotes herein any of two ormore alternative forms of a gene occupying the same chromosomal locus.Allelic variation arises naturally through mutation, and may result inpolymorphism within populations. Gene mutations can be silent (no changein the encoded polypeptide) or may encode polypeptides having alteredamino acid sequences. An allelic variant of a polypeptide is apolypeptide encoded by an allelic variant of a gene.

Substantially pure polynucleotide: The term “substantially purepolynucleotide” as used herein refers to a polynucleotide preparationfree of other extraneous or unwanted nucleotides and in a form suitablefor use within genetically engineered protein production systems. Thus,a substantially pure polynucleotide contains at most 10%, preferably atmost 8%, more preferably at most 6%, more preferably at most 5%, morepreferably at most 4%, more preferably at most 3%, even more preferablyat most 2%, most preferably at most 1%, and even most preferably at most0.5% by weight of other polynucleotide material with which it isnatively associated. A substantially pure polynucleotide may, however,include naturally occurring 5′ and 3′ untranslated regions, such aspromoters and terminators. It is preferred that the substantially purepolynucleotide is at least 90% pure, preferably at least 92% pure, morepreferably at least 94% pure, more preferably at least 95% pure, morepreferably at least 96% pure, more preferably at least 97% pure, evenmore preferably at least 98% pure, most preferably at least 99%, andeven most preferably at least 99.5% pure by weight. The polynucleotidesof the present invention are preferably in a substantially pure form. Inparticular, it is preferred that the polynucleotides disclosed hereinare in “essentially pure form”, i.e., that the polynucleotidepreparation is essentially free of other polynucleotide material withwhich it is natively associated. Herein, the term “substantially purepolynucleotide” is synonymous with the terms “isolated polynucleotide”and “polynucleotide in isolated form.” The polynucleotides may be ofgenomic, cDNA, RNA, semisynthetic, synthetic origin, or any combinationsthereof.

cDNA: The term “cDNA” is defined herein as a DNA molecule which can beprepared by reverse transcription from a mature, spliced, mRNA moleculeobtained from a eukaryotic cell. cDNA lacks intron sequences that areusually present in the corresponding genomic DNA. The initial, primaryRNA transcript is a precursor to mRNA which is processed through aseries of steps before appearing as mature spliced mRNA. These stepsinclude the removal of intron sequences by a process called splicing.cDNA derived from mRNA lacks, therefore, any intron sequences.

Nucleic acid construct: The term “nucleic acid construct” as used hereinrefers to a nucleic acid molecule, either single- or double-stranded,which is isolated from a naturally occurring gene or which is modifiedto contain segments of nucleic acids in a manner that would nototherwise exist in nature. The term nucleic acid construct is synonymouswith the term “expression cassette” when the nucleic acid constructcontains the control sequences required for expression of a codingsequence of the present invention.

Control sequence: The term “control sequences” is defined herein toinclude all components, which are necessary or advantageous for theexpression of a polynucleotide encoding a polypeptide of the presentinvention. Each control sequence may be native or foreign to thenucleotide sequence encoding the polypeptide. Such control sequencesinclude, but are not limited to, a leader, polyadenylation sequence,propeptide sequence, promoter, signal peptide sequence, andtranscription terminator. At a minimum, the control sequences include apromoter, and transcriptional and translational stop signals. Thecontrol sequences may be provided with linkers for the purpose ofintroducing specific restriction sites facilitating ligation of thecontrol sequences with the coding region of the nucleotide sequenceencoding a polypeptide.

Operably linked: The term “operably linked” denotes herein aconfiguration in which a control sequence is placed at an appropriateposition relative to the coding sequence of the polynucleotide sequencesuch that the control sequence directs the expression of the codingsequence of a polypeptide.

Coding sequence: When used herein the term “coding sequence” means anucleotide sequence, which directly specifies the amino acid sequence ofits protein product. The boundaries of the coding sequence are generallydetermined by an open reading frame, which usually begins with the ATGstart codon or alternative start codons such as GTG and TTG. The codingsequence may a DNA, cDNA, or recombinant nucleotide sequence.

Expression: The term “expression” includes any step involved in theproduction of the polypeptide including, but not limited to,transcription, post-transcriptional modification, translation,post-translational modification, and secretion.

Expression vector: The term “expression vector” is defined herein as alinear or circular DNA molecule that comprises a polynucleotide encodinga polypeptide of the invention, and which is operably linked toadditional nucleotides that provide for its expression.

Host cell: The term “host cell”, as used herein, includes any cell typewhich is susceptible to transformation, transfection, transduction, andthe like with a nucleic acid construct comprising a polynucleotide ofthe present invention.

Modification: The term “modification” means herein any chemicalmodification of the polypeptide consisting of the amino acids 2 to 148of SEQ ID NO: 5 as well as genetic manipulation of the DNA encoding thatpolypeptide. The modification(s) can be substitution(s), deletion(s)and/or insertions(s) of the amino acid(s) as well as replacement(s) ofamino acid side chain(s).

Artificial variant: When used herein, the term “artificial variant”means a polypeptide having protease activity produced by an organismexpressing a modified nucleotide sequence of SEQ ID NO: 4. The modifiednucleotide sequence is obtained through human intervention bymodification of the nucleotide sequence disclosed in SEQ ID NO: 4.

DETAILED DESCRIPTION OF THE INVENTION

Polypeptides Having Protease Activity

In a first aspect, the present invention relates to isolatedpolypeptides having an amino acid sequence which has a degree ofidentity to amino acids 2 to 148 of SEQ ID NO: 5 (i.e., the maturepolypeptide) of at least 95%, such as preferably 96%, such as preferablyat least 97%, such as preferably 98%, such as preferably 99% and such aspreferably 99.5% which have protease activity (hereinafter “homologouspolypeptides”). In a preferred aspect, the homologous polypeptides havean amino acid sequence which differs by five amino acids, preferably byfour amino acids, more preferably by three amino acids, even morepreferably by two amino acids, and most preferably by one amino acidfrom amino acids 2 to 148 of SEQ ID NO: 5.

A polypeptide of the present invention preferably comprises the aminoacid sequence of SEQ ID NO: 5 or an allelic variant thereof; or afragment thereof that has protease activity. In a preferred aspect, apolypeptide comprises the amino acid sequence of SEQ ID NO: 5. Inanother preferred aspect, a polypeptide comprises amino acids 2 to 148of SEQ ID NO: 5, or an allelic variant thereof; or a fragment thereofthat has protease activity. In another preferred aspect, a polypeptidecomprises amino acids 2 to 148 of SEQ ID NO: 5. In another preferredaspect, a polypeptide consists of the amino acid sequence of SEQ ID NO:5 or an allelic variant thereof; or a fragment thereof that has proteaseactivity. In another preferred aspect, a polypeptide consists of theamino acid sequence of SEQ ID NO: 5. In another preferred aspect, apolypeptide consists of amino acids 2 to 148 of SEQ ID NO: 5 or anallelic variant thereof; or a fragment thereof that has proteaseactivity. In another preferred aspect, a polypeptide consists of aminoacids 2 to 148 of SEQ ID NO: 5.

The nucleotide sequence of SEQ ID NO: 4 or a subsequence thereof, aswell as the amino acid sequence of SEQ ID NO: 5 or a fragment thereof,may be used to design a nucleic acid probe to identify and clone DNAencoding polypeptides having protease activity from strains of differentgenera or species according to methods well known in the art. Inparticular, such probes can be used for hybridization with the genomicor cDNA of the genus or species of interest, following standard Southernblotting procedures, in order to identify and isolate the correspondinggene therein. Such probes can be considerably shorter than the entiresequence, but should be at least 14, preferably at least 25, morepreferably at least 35, and most preferably at least 70 nucleotides inlength. It is however, preferred that the nucleic acid probe is at least100 nucleotides in length. For example, the nucleic acid probe may be atleast 200 nucleotides, preferably at least 300 nucleotides, morepreferably at least 400 nucleotides, or most preferably at least 500nucleotides in length. Even longer probes may be used, e.g., nucleicacid probes which are at least 600 nucleotides, at least preferably atleast 700 nucleotides, more preferably at least 800 nucleotides, or mostpreferably at least 900 nucleotides in length. Both DNA and RNA probescan be used. The probes are typically labelled for detecting thecorresponding gene (for example, with ³²P, ³H, ³⁵S, biotin, or avidin).Such probes are encompassed by the present invention.

A genomic DNA or cDNA library prepared from such other organisms may,therefore, be screened for DNA which hybridizes with the probesdescribed above and which encodes a polypeptide having proteaseactivity. Genomic or other DNA from such other organisms may beseparated by agarose or polyacrylamide gel electrophoresis, or otherseparation techniques. DNA from the libraries or the separated DNA maybe transferred to and immobilized on nitrocellulose or other suitablecarrier material. In order to identify a clone or DNA which ishomologous with SEQ ID NO: 4 or a subsequence thereof, the carriermaterial is used in a Southern blot.

For purposes of the present invention, hybridization indicates that thenucleotide sequence hybridizes to a labelled nucleic acid probecorresponding to the nucleotide sequence shown in SEQ ID NO: 4, itscomplementary strand, or a subsequence thereof, under medium to veryhigh stringency conditions. Molecules to which the nucleic acid probehybridizes under these conditions can be detected using X-ray film.

For long probes of at least 100 nucleotides in length, medium to veryhigh stringency conditions are defined as prehybridization andhybridization at 42° C. in 5×SSPE, 0.3% SDS, 200 μg/ml sheared anddenatured salmon sperm DNA, and either 35% formamide for medium andmedium-high stringencies, or 50% formamide for high and very highstringencies, following standard Southern blotting procedures for 12 to24 hours optimally.

For long probes of at least 100 nucleotides in length, the carriermaterial is finally washed three times each for 15 minutes using 2×SSC,0.2% SDS preferably at least at 55° C. (medium stringency), morepreferably at least at 60° C. (medium-high stringency), even morepreferably at least at 65° C. (high stringency), and most preferably atleast at 70° C. (very high stringency).

In a particular embodiment, the wash is conducted using 0.2×SSC, 0.2%SDS preferably at least at 55° C. (medium stringency), more preferablyat least at 60° C. (medium-high stringency), even more preferably atleast at 65° C. (high stringency), and most preferably at least at 70°C. (very high stringency). In another particular embodiment, the wash isconducted using 0.1×SSC, 0.2% SDS preferably at least at 55° C. (mediumstringency), more preferably at least at 60° C. (medium-highstringency), even more preferably at least at 65° C. (high stringency),and most preferably at least at 70° C. (very high stringency).

For short probes which are about 15 nucleotides to about 70 nucleotidesin length, stringency conditions are defined as prehybridization,hybridization, and washing post-hybridization at about 5° C. to about10° C. below the calculated T_(m) using the calculation according toBolton and McCarthy (1962, Proceedings of the National Academy ofSciences USA 48:1390) in 0.9 M NaCl, 0.09 M Tris-HCl pH 7.6, 6 mM EDTA,0.5% NP-40, 1× Denhardt's solution, 1 mM sodium pyrophosphate, 1 mMsodium monobasic phosphate, 0.1 mM ATP, and 0.2 mg of yeast RNA per mlfollowing standard Southern blotting procedures.

For short probes which are about 15 nucleotides to about 70 nucleotidesin length, the carrier material is washed once in 6×SCC plus 0.1% SDSfor 15 minutes and twice each for 15 minutes using 6×SSC at 5° C. to 10°C. below the calculated T_(m).

Under salt-containing hybridization conditions, the effective T_(m) iswhat controls the degree of identity required between the probe and thefilter bound DNA for successful hybridization. The effective T_(m) maybe determined using the formula below to determine the degree ofidentity required for two DNAs to hybridize under various stringencyconditions.Effective T _(m)=81.5+16.6(log M[Na⁺])+0.41(% G+C)−0.72(% formamide)

The G+C content of SEQ ID NO: 4 or nucleotides 1 to 518 of SEQ ID NO: 4is 55%. For medium stringency, the formamide is 35% and the Na⁺concentration for 5×SSPE is 0.75 M. Applying this formula to thesevalues, the Effective T_(m) is 77° C.

Another relevant relationship is that a 1% mismatch of two DNAs lowersthe T_(m) by 1.4° C. To determine the degree of identity required fortwo DNAs to hybridize under medium stringency conditions at 42° C., thefollowing formula is used:% Homology=100−[(Effective T _(m)−Hybridization Temperature)/1.4]

Applying this formula to the values, the degree of identity required fortwo DNAs to hybridize under medium stringency conditions at 42° C. is100−[(77−42)/1.4]=75%.

In a second aspect, the present invention relates to isolatedpolypeptides having protease activity encoded by a polynucleotidecomprising nucleotides 1 to 515 of SEQ ID NO: 4, as a unique motif.

In a fourth aspect, the present invention relates to isolatedpolypeptides having the following physicochemical properties:

-   -   a pH optimum between 8 and 9;    -   a molecular weight about 19 kDa;    -   not inhibited by leupeptin, pepstatin,        4-(2-aminoethyl)-benzenesulfonyl fluoride (AEBSF), ZnSO₄ and        EDTA;    -   having high activity on the substrate Suc-LLVY-MCA and low        activity on the substrates: Glt-AAF-MCA, Boc-FSR-MCA,        Suc(OMe)-AAPV-MCA and Z-LLE-MCA.

In a third aspect, the present invention relates to artificial variantscomprising a conservative substitution, deletion, and/or insertion ofone or more amino acids of SEQ ID NO: 5 or the mature polypeptidethereof. Preferably, amino acid changes are of a minor nature, that isconservative amino acid substitutions or insertions that do notsignificantly affect the folding and/or activity of the protein; smalldeletions, typically of one to about 30 amino acids; small amino- orcarboxyl-terminal extensions, such as an amino-terminal methionineresidue; a small linker peptide of up to about 20-25 residues; or asmall extension that facilitates purification by changing net charge oranother function, such as a poly-histidine tract, an antigenic epitopeor a binding domain.

Examples of conservative substitutions are within the group of basicamino acids (arginine, lysine and histidine), acidic amino acids(glutamic acid and aspartic acid), polar amino acids (glutamine andasparagine), hydrophobic amino acids (leucine, isoleucine and valine),aromatic amino acids (phenylalanine, tryptophan and tyrosine), and smallamino acids (glycine, alanine, serine, threonine and methionine). Aminoacid substitutions which do not generally alter specific activity areknown in the art and are described, for example, by H. Neurath and R. L.Hill, 1979, In, The Proteins, Academic Press, New York. The mostcommonly occurring exchanges are Ala/Ser, Val/Ile, Asp/Glu, Thr/Ser,Ala/Gly, Ala/Thr, Ser/Asn, Ala/Val, Ser/Gly, Tyr/Phe, Ala/Pro, Lys/Arg,Asp/Asn, Leu/Ile, Leu/Val, Ala/Glu, and Asp/Gly.

In addition to the 20 standard amino acids, non-standard amino acids(such as 4-hydroxyproline, 6-N-methyl lysine, 2-aminoisobutyric acid,isovaline, and alpha-methyl serine) may be substituted for amino acidresidues of a wild-type polypeptide. A limited number ofnon-conservative amino acids, amino acids that are not encoded by thegenetic code, and unnatural amino acids may be substituted for aminoacid residues. “Unnatural amino acids” have been modified after proteinsynthesis, and/or have a chemical structure in their side chain(s)different from that of the standard amino acids. Unnatural amino acidscan be chemically synthesized, and preferably, are commerciallyavailable, and include pipecolic acid, thiazolidine carboxylic acid,dehydroproline, 3- and 4-methylproline, and 3,3-dimethylproline.

Alternatively, the amino acid changes are of such a nature that thephysical-chemical properties of the polypeptides are altered. Forexample, amino acid changes may improve the thermal stability of thepolypeptide, alter the substrate specificity, change the pH optimum, andthe like.

Essential amino acids in the parent polypeptide can be identifiedaccording to procedures known in the art, such as site-directedmutagenesis or alanine-scanning mutagenesis (Cunningham and Wells, 1989,Science 244: 1081-1085). In the latter technique, single alaninemutations are introduced at every residue in the molecule, and theresultant mutant molecules are tested for biological activity (i.e.,protease activity) to identify amino acid residues that are critical tothe activity of the molecule. See also, Hilton et al., 1996, J. Biol.Chem. 271: 4699-4708. The active site of the enzyme or other biologicalinteraction can also be determined by physical analysis of structure, asdetermined by such techniques as nuclear magnetic resonance,crystallography, electron diffraction, or photoaffinity labeling, inconjunction with mutation of putative contact site amino acids. See, forexample, de Vos et al., 1992, Science 255: 306-312; Smith et al., 1992,J. Mol. Biol. 224: 899-904; Wlodaver et al., 1992, FEBS Lett. 309:59-64.The identities of essential amino acids can also be inferred fromanalysis of identities with polypeptides which are related to apolypeptide according to the invention.

Single or multiple amino acid substitutions can be made and tested usingknown methods of mutagenesis, recombination, and/or shuffling, followedby a relevant screening procedure, such as those disclosed byReidhaar-Olson and Sauer, 1988, Science 241: 53-57; Bowie and Sauer,1989, Proc. Natl. Acad. Sci. USA 86: 2152-2156; WO 95/17413; or WO95/22625. Other methods that can be used include error-prone PCR, phagedisplay (e.g., Lowman et al., 1991, Biochem. 30:10832-10837; U.S. Pat.No. 5,223,409; WO 92/06204), and region-directed mutagenesis (Derbyshireet al., 1986, Gene 46:145; Ner et al., 1988, DNA 7:127).

Mutagenesis/shuffling methods can be combined with high-throughput,automated screening methods to detect activity of cloned, mutagenizedpolypeptides expressed by host cells. Mutagenized DNA molecules thatencode active polypeptides can be recovered from the host cells andrapidly sequenced using standard methods in the art. These methods allowthe rapid determination of the importance of individual amino acidresidues in a polypeptide of interest, and can be applied topolypeptides of unknown structure.

The total number of amino acid substitutions, deletions and/orinsertions of amino acids 2 to 148 of SEQ ID NO: 5 is at most 6,preferably at most 5, more preferably 4, even more preferably 3, mostpreferably 2, and even most preferably 1.

Sources of Polypeptides Having Protease Activity

A polypeptide of the present invention may be obtained frommicroorganisms of any genus. For purposes of the present invention, theterm “obtained from” as used herein in connection with a given sourceshall mean that the polypeptide encoded by a nucleotide sequence isproduced by the source or by a strain in which the nucleotide sequencefrom the source has been inserted. In a preferred aspect, thepolypeptide obtained from a given source is secreted extracellularly.

A polypeptide of the present invention may be a fungal polypeptide, andmore preferably a yeast polypeptide such as a Candida, Kluyveromyces,Pichia, Saccharomyces, Schizosaccharomyces, or Yarrowia polypeptide; ormore preferably a filamentous fungal polypeptide such as an Acremonium,Aspergillus, Aureobasidium, Cryptococcus, Filobasidium, Fusarium,Humicola, Magnaporthe, Mucor, Myceliophthora, Neocallimastix,Neurospora, Paecilomyces, Penicillium, Piromyces, Schizophyllum,Talaromyces, Thermoascus, Thielavia, Tolypocladium, or Trichodermapolypeptide.

In a preferred aspect, the polypeptide is a Saccharomycescarlsbergensis, Saccharomyces cerevisiae, Saccharomyces diastaticus,Saccharomyces douglasii, Saccharomyces kluyveri, Saccharomycesnorbensis, or Saccharomyces oviformis polypeptide having proteaseactivity.

In another preferred aspect, the polypeptide is an Aspergillusaculeatus, Aspergillus awamori, Aspergillus fumigatus, Aspergillusfoetidus, Aspergillus japonicus, Aspergillus nidulans, Aspergillusniger, Aspergillus oryzae, Fusarium bactridioides, Fusarium cerealis,Fusarium crookwellense, Fusarium culmorum, Fusarium graminearum,Fusarium graminum, Fusarium heterosporum, Fusarium negundi, Fusariumoxysporum, Fusarium reticulatum, Fusarium roseum, Fusarium sambucinum,Fusarium sarcochroum, Fusarium sporotrichioides, Fusarium sulphureum,Fusarium torulosum, Fusarium trichothecioides, Fusarium venenatum,Humicola insolens, Humicola lanuginosa, Mucor miehei, Myceliophthorathermophila, Neurospora crassa, Penicillium purpurogenum, Trichodermaharzianum, Trichoderma koningii, Trichoderma longibrachiatum,Trichoderma reesei, or Trichoderma viride polypeptide.

In another preferred aspect, the polypeptide is an Aspergillus,Aspergillus niger, or Aspergillus oryzae polypeptide.

In a more preferred aspect, the polypeptide is an Aspergillus nigerpolypeptide, e.g., the polypeptide of SEQ ID NO: 5.

It will be understood that for the aforementioned species, the inventionencompasses both the perfect and imperfect states, and other taxonomicequivalents, e.g., anamorphs, regardless of the species name by whichthey are known. Those skilled in the art will readily recognize theidentity of appropriate equivalents.

Strains of these species are readily accessible to the public in anumber of culture collections, such as the American Type CultureCollection (ATCC), Deutsche Sammlung von Mikroorganismen andZellkulturen GmbH (DSMZ), Centraalbureau Voor Schimmelcultures (CBS),and Agricultural Research Service Patent Culture Collection, NorthernRegional Research Center (NRRL).

Furthermore, such polypeptides may be identified and obtained from othersources including microorganisms isolated from nature (e.g., soil,composts, water, etc.) using the above-mentioned probes. Techniques forisolating microorganisms from natural habitats are well known in theart. The polynucleotide may then be obtained by similarly screening agenomic or cDNA library of another microorganism. Once a polynucleotidesequence encoding a polypeptide has been detected with the probe(s), thepolynucleotide can be isolated or cloned by utilizing techniques whichare well known to those of ordinary skill in the art (see, e.g.,Sambrook et al., 1989, supra).

Polypeptides of the present invention also include fused polypeptides orcleavable fusion polypeptides in which another polypeptide is fused atthe N-terminus or the C-terminus of the polypeptide or fragment thereof.A fused polypeptide is produced by fusing a nucleotide sequence (or aportion thereof) encoding another polypeptide to a nucleotide sequence(or a portion thereof) of the present invention. Techniques forproducing fusion polypeptides are known in the art, and include ligatingthe coding sequences encoding the polypeptides so that they are in frameand that expression of the fused polypeptide is under control of thesame promoter(s) and terminator.

Polynucleotides

The present invention also relates to isolated polynucleotides having anucleotide sequence which encode a polypeptide of the present invention.In a preferred aspect, the nucleotide sequence is set forth in SEQ IDNO: 4. In another preferred aspect, the nucleotide sequence is themature polypeptide coding region of SEQ ID NO: 4. The present inventionalso encompasses nucleotide sequences which encode a polypeptide havingthe amino acid sequence of SEQ ID NO: 5 or the mature polypeptidethereof, which differ from SEQ ID NO: 4 by virtue of the degeneracy ofthe genetic code. The present invention also relates to subsequences ofSEQ ID NO: 4 which encode fragments of SEQ ID NO: 5 that have proteaseactivity.

The present invention also relates to mutant polynucleotides comprisingat least one mutation in the mature polypeptide coding sequence of SEQID NO: 4, in which the mutant nucleotide sequence encodes a polypeptidewhich consists of amino acids 2 to 148 of SEQ ID NO: 2.

The techniques used to isolate or clone a polynucleotide encoding apolypeptide are known in the art and include isolation from genomic DNA,preparation from cDNA, or a combination thereof. The cloning of thepolynucleotides of the present invention from such genomic DNA can beeffected, e.g., by using the well known polymerase chain reaction (PCR)or antibody screening of expression libraries to detect cloned DNAfragments with shared structural features. See, e.g., Innis et al.,1990, PCR: A Guide to Methods and Application, Academic Press, New York.Other nucleic acid amplification procedures such as ligase chainreaction (LCR), ligated activated transcription (LAT) and nucleotidesequence-based amplification (NASBA) may be used. The polynucleotidesmay be cloned from a strain of Aspergillus, or another or relatedorganism and thus, for example, may be an allelic or species variant ofthe polypeptide encoding region of the nucleotide sequence.

The present invention also relates to polynucleotides having nucleotidesequences which have a degree of identity to the mature polypeptidecoding sequence of SEQ ID NO: 4 (i.e., nucleotides 4 to 518) of at least60%, preferably at least 65%, more preferably at least 70%, morepreferably at least 75%, more preferably at least 80%, more preferablyat least 85%, more preferably at least 90%, even more preferably atleast 95%, and most preferably at least 97% identity, which encode anactive polypeptide.

Modification of a nucleotide sequence encoding a polypeptide of thepresent invention may be necessary for the synthesis of polypeptidessubstantially similar to the polypeptide. The term “substantiallysimilar” to the polypeptide refers to non-naturally occurring forms ofthe polypeptide. These polypeptides may differ in some engineered wayfrom the polypeptide isolated from its native source, e.g., artificialvariants that differ in specific activity, thermostability, pH optimum,or the like. The variant sequence may be constructed on the basis of thenucleotide sequence presented as the polypeptide encoding region of SEQID NO: 4, e.g., a subsequence thereof, and/or by introduction ofnucleotide substitutions which do not give rise to another amino acidsequence of the polypeptide encoded by the nucleotide sequence, butwhich correspond to the codon usage of the host organism intended forproduction of the enzyme, or by introduction of nucleotide substitutionswhich may give rise to a different amino acid sequence. For a generaldescription of nucleotide substitution, see, e.g., Ford et al., 1991,Protein Expression and Purification 2: 95-107.

It will be apparent to those skilled in the art that such substitutionscan be made outside the regions critical to the function of the moleculeand still result in an active polypeptide. Amino acid residues essentialto the activity of the polypeptide encoded by an isolated polynucleotideof the invention, and therefore preferably not subject to substitution,may be identified according to procedures known in the art, such assite-directed mutagenesis or alanine-scanning mutagenesis (see, e.g.,Cunningham and Wells, 1989, Science 244: 1081-1085). In the lattertechnique, mutations are introduced at every positively charged residuein the molecule, and the resultant mutant molecules are tested forprotease activity to identify amino acid residues that are critical tothe activity of the molecule. Sites of substrate-enzyme interaction canalso be determined by analysis of the three-dimensional structure asdetermined by such techniques as nuclear magnetic resonance analysis,crystallography or photoaffinity labelling (see, e.g., de Vos et al.,1992, Science 255: 306-312; Smith et al., 1992, Journal of MolecularBiology 224: 899-904; Wlodaver et al., 1992, FEBS Letters 309: 59-64).

The present invention also relates to isolated polynucleotides encodinga polypeptide of the present invention, which hybridize under mediumstringency conditions, more preferably medium-high stringencyconditions, even more preferably high stringency conditions, and mostpreferably very high stringency conditions with nucleotides 4 to 518 ofSEQ ID NO: 4, a complementary strand thereof; or allelic variants andsubsequences thereof (Sambrook et al., 1989, supra), as defined herein.

Nucleic Acid Constructs

The present invention also relates to nucleic acid constructs comprisingan isolated polynucleotide of the present invention operably linked toone or more control sequences which direct the expression of the codingsequence in a suitable host cell under conditions compatible with thecontrol sequences.

An isolated polynucleotide encoding a polypeptide of the presentinvention may be manipulated in a variety of ways to provide forexpression of the polypeptide. Manipulation of the polynucleotide'ssequence prior to its insertion into a vector may be desirable ornecessary depending on the expression vector. The techniques formodifying polynucleotide sequences utilizing recombinant DNA methods arewell known in the art.

The control sequence may be an appropriate promoter sequence, anucleotide sequence which is recognized by a host cell for expression ofa polynucleotide encoding a polypeptide of the present invention. Thepromoter sequence contains transcriptional control sequences whichmediate the expression of the polypeptide. The promoter may be anynucleotide sequence which shows transcriptional activity in the hostcell of choice including mutant, truncated, and hybrid promoters, andmay be obtained from genes encoding extracellular or intracellularpolypeptides either homologous or heterologous to the host cell.

Examples of suitable promoters for directing the transcription of thenucleic acid constructs of the present invention in a filamentous fungalhost cell are promoters obtained from the genes for Aspergillus oryzaeTAKA amylase, Rhizomucor miehei aspartic proteinase, Aspergillus nigerneutral alpha-amylase, Aspergillus niger acid stable alpha-amylase,Aspergillus niger or Aspergillus awamori glucoamylase (glaA), Rhizomucormiehei lipase, Aspergillus oryzae alkaline protease, Aspergillus oryzaetriose phosphate isomerase, Aspergillus nidulans acetamidase, Fusariumvenenatum amyloglucosidase (WO 00/56900), Fusarium venenatum Daria (WO00/56900), Fusarium venenatum Quinn (WO 00/56900), Fusarium oxysporumtrypsin-like protease (WO 96/00787), Trichoderma reeseibeta-glucosidase, Trichoderma reesei cellobiohydrolase I, Trichodermareesei endoglucanase I, Trichoderma reesei endoglucanase II, Trichodermareesei endoglucanase III, Trichoderma reesei endoglucanase IV,Trichoderma reesei endoglucanase V, Trichoderma reesei xylanase I,Trichoderma reesei xylanase II, Trichoderma reesei beta-xylosidase, aswell as the NA2-tpi promoter (a hybrid of the promoters from the genesfor Aspergillus niger neutral alpha-amylase and Aspergillus oryzaetriose phosphate isomerase); and mutant, truncated, and hybrid promotersthereof.

In a yeast host, useful promoters are obtained from the genes forSaccharomyces cerevisiae enolase (ENO-1), Saccharomyces cerevisiaegalactokinase (GAL1), Saccharomyces cerevisiae alcoholdehydrogenase/glyceraldehyde-3-phosphate dehydrogenase (ADH1,ADH2/GAP),Saccharomyces cerevisiae triose phosphate isomerase (TPI), Saccharomycescerevisiae metallothionine (CUP1), and Saccharomyces cerevisiae3-phosphoglycerate kinase. Other useful promoters for yeast host cellsare described by Romanos et al., 1992, Yeast 8: 423-488.

The control sequence may also be a suitable transcription terminatorsequence, a sequence recognized by a host cell to terminatetranscription. The terminator sequence is operably linked to the 3′terminus of the nucleotide sequence encoding the polypeptide. Anyterminator which is functional in the host cell of choice may be used inthe present invention.

Preferred terminators for filamentous fungal host cells are obtainedfrom the genes for Aspergillus oryzae TAKA amylase, Aspergillus nigerglucoamylase, Aspergillus nidulans anthranilate synthase, Aspergillusniger alpha-glucosidase, and Fusarium oxysporum trypsin-like protease.

Preferred terminators for yeast host cells are obtained from the genesfor Saccharomyces cerevisiae enolase, Saccharomyces cerevisiaecytochrome C (CYC1), and Saccharomyces cerevisiaeglyceraldehyde-3-phosphate dehydrogenase. Other useful terminators foryeast host cells are described by Romanos et al., 1992, supra.

The control sequence may also be a suitable leader sequence, anontranslated region of an mRNA which is important for translation bythe host cell. The leader sequence is operably linked to the 5′ terminusof the nucleotide sequence encoding the polypeptide. Any leader sequencethat is functional in the host cell of choice may be used in the presentinvention.

Preferred leaders for filamentous fungal host cells are obtained fromthe genes for Aspergillus oryzae TAKA amylase and Aspergillus nidulanstriose phosphate isomerase.

Suitable leaders for yeast host cells are obtained from the genes forSaccharomyces cerevisiae enolase (ENO-1), Saccharomyces cerevisiae3-phosphoglycerate kinase, Saccharomyces cerevisiae alpha-factor, andSaccharomyces cerevisiae alcoholdehydrogenase/glyceraldehyde-3-phosphate dehydrogenase (ADH2/GAP).

The control sequence may also be a polyadenylation sequence, a sequenceoperably linked to the 3′ terminus of the nucleotide sequence and which,when transcribed, is recognized by the host cell as a signal to addpolyadenosine residues to transcribed mRNA. Any polyadenylation sequencewhich is functional in the host cell of choice may be used in thepresent invention.

Preferred polyadenylation sequences for filamentous fungal host cellsare obtained from the genes for Aspergillus oryzae TAKA amylase,Aspergillus niger glucoamylase, Aspergillus nidulans anthranilatesynthase, Fusarium oxysporum trypsin-like protease, and Aspergillusniger alpha-glucosidase.

Useful polyadenylation sequences for yeast host cells are described byGuo and Sherman, 1995, Molecular Cellular Biology 15: 5983-5990.

The control sequence may also be a signal peptide coding region thatcodes for an amino acid sequence linked to the amino terminus of apolypeptide and directs the encoded polypeptide into the cell'ssecretory pathway. The 5′ end of the coding sequence of the nucleotidesequence may inherently contain a signal peptide coding region naturallylinked in translation reading frame with the segment of the codingregion which encodes the secreted polypeptide. Alternatively, the 5′ endof the coding sequence may contain a signal peptide coding region whichis foreign to the coding sequence. The foreign signal peptide codingregion may be required where the coding sequence does not naturallycontain a signal peptide coding region. Alternatively, the foreignsignal peptide coding region may simply replace the natural signalpeptide coding region in order to enhance secretion of the polypeptide.However, any signal peptide coding region which directs the expressedpolypeptide into the secretory pathway of a host cell of choice may beused in the present invention.

Effective signal peptide coding regions for filamentous fungal hostcells are the signal peptide coding regions obtained from the genes forAspergillus oryzae TAKA amylase, Aspergillus niger neutral amylase,Aspergillus niger glucoamylase, Rhizomucor miehei aspartic proteinase,Humicola insolens cellulase, and Humicola lanuginosa lipase.

Useful signal peptides for yeast host cells are obtained from the genesfor Saccharomyces cerevisiae alpha-factor and Saccharomyces cerevisiaeinvertase. Other useful signal peptide coding regions are described byRomanos et al., 1992, supra.

The control sequence may also be a propeptide coding region that codesfor an amino acid sequence positioned at the amino terminus of apolypeptide. The resultant polypeptide is known as a proenzyme orpropolypeptide (or a zymogen in some cases). A propolypeptide isgenerally inactive and can be converted to a mature active polypeptideby catalytic or autocatalytic cleavage of the propeptide from thepropolypeptide. The propeptide coding region may be obtained from thegenes for Bacillus subtilis alkaline protease (aprE), Bacillus subtilisneutral protease (nprT), Saccharomyces cerevisiae alpha-factor,Rhizomucor miehei aspartic proteinase, and Myceliophthora thermophilalaccase (WO 95/33836).

Where both signal peptide and propeptide regions are present at theamino terminus of a polypeptide, the propeptide region is positionednext to the amino terminus of a polypeptide and the signal peptideregion is positioned next to the amino terminus of the propeptideregion.

It may also be desirable to add regulatory sequences which allow theregulation of the expression of the polypeptide relative to the growthof the host cell. Examples of regulatory systems are those which causethe expression of the gene to be turned on or off in response to achemical or physical stimulus, including the presence of a regulatorycompound. In yeast, the ADH2 system or GAL1 system may be used. Infilamentous fungi, the TAKA alpha-amylase promoter, Aspergillus nigerglucoamylase promoter, and Aspergillus oryzae glucoamylase promoter maybe used as regulatory sequences. Other examples of regulatory sequencesare those which allow for gene amplification. In eukaryotic systems,these include the dihydrofolate reductase gene which is amplified in thepresence of methotrexate, and the metallothionein genes which areamplified with heavy metals. In these cases, the nucleotide sequenceencoding the polypeptide would be operably linked with the regulatorysequence.

Expression Vectors

The present invention also relates to recombinant expression vectorscomprising a polynucleotide of the present invention, a promoter, andtranscriptional and translational stop signals. The various nucleicacids and control sequences described above may be joined together toproduce a recombinant expression vector which may include one or moreconvenient restriction sites to allow for insertion or substitution ofthe nucleotide sequence encoding the polypeptide at such sites.Alternatively, a nucleotide sequence of the present invention may beexpressed by inserting the nucleotide sequence or a nucleic acidconstruct comprising the sequence into an appropriate vector forexpression. In creating the expression vector, the coding sequence islocated in the vector so that the coding sequence is operably linkedwith the appropriate control sequences for expression.

The recombinant expression vector may be any vector (e.g., a plasmid orvirus) which can be conveniently subjected to recombinant DNA proceduresand can bring about expression of the nucleotide sequence. The choice ofthe vector will typically depend on the compatibility of the vector withthe host cell into which the vector is to be introduced. The vectors maybe linear or closed circular plasmids.

The vector may be an autonomously replicating vector, i.e., a vectorwhich exists as an extrachromosomal entity, the replication of which isindependent of chromosomal replication, e.g., a plasmid, anextrachromosomal element, a minichromosome, or an artificial chromosome.The vector may contain any means for assuring self-replication.Alternatively, the vector may be one which, when introduced into thehost cell, is integrated into the genome and replicated together withthe chromosome(s) into which it has been integrated. Furthermore, asingle vector or plasmid or two or more vectors or plasmids whichtogether contain the total DNA to be introduced into the genome of thehost cell, or a transposon may be used.

The vectors of the present invention preferably contain one or moreselectable markers which permit easy selection of transformed cells. Aselectable marker is a gene the product of which provides for biocide orviral resistance, resistance to heavy metals, prototrophy to auxotrophs,and the like.

Suitable markers for yeast host cells are ADE2, HIS3, LEU2, LYS2, MET3,TRP1, and URA3. Selectable markers for use in a filamentous fungal hostcell include, but are not limited to, amdS (acetamidase), argB(ornithine carbamoyltransferase), bar (phosphinothricinacetyltransferase), hph (hygromycin phosphotransferase), niaD (nitratereductase), pyrG (orotidine-5′-phosphate decarboxylase), sC (sulfateadenyltransferase), and trpC (anthranilate synthase), as well asequivalents thereof. Preferred for use in an Aspergillus cell are theamdS and pyrG genes of Aspergillus nidulans or Aspergillus oryzae andthe bar gene of Streptomyces hygroscopicus.

The vectors of the present invention preferably contain an element(s)that permits integration of the vector into the host cell's genome orautonomous replication of the vector in the cell independent of thegenome.

For integration into the host cell genome, the vector may rely on thepolynucleotide's sequence encoding the polypeptide or any other elementof the vector for integration into the genome by homologous ornonhomologous recombination. Alternatively, the vector may containadditional nucleotide sequences for directing integration by homologousrecombination into the genome of the host cell at a precise location(s)in the chromosome(s). To increase the likelihood of integration at aprecise location, the integrational elements should preferably contain asufficient number of nucleic acids, such as 100 to 10,000 base pairs,preferably 400 to 10,000 base pairs, and most preferably 800 to 10,000base pairs, which have a high degree of identity with the correspondingtarget sequence to enhance the probability of homologous recombination.The integrational elements may be any sequence that is homologous withthe target sequence in the genome of the host cell. Furthermore, theintegrational elements may be non-encoding or encoding nucleotidesequences. On the other hand, the vector may be integrated into thegenome of the host cell by non-homologous recombination.

For autonomous replication, the vector may further comprise an origin ofreplication enabling the vector to replicate autonomously in the hostcell in question. The origin of replication may be any plasmidreplicator mediating autonomous replication which functions in a cell.The term “origin of replication” or “plasmid replicator” is definedherein as a nucleotide sequence that enables a plasmid or vector toreplicate in vivo.

Examples of origins of replication for use in a yeast host cell are the2 micron origin of replication, ARS1, ARS4, the combination of ARS1 andCEN3, and the combination of ARS4 and CEN6.

Examples of origins of replication useful in a filamentous fungal cellare AMA1 and ANS1 (Gems et al., 1991, Gene 98:61-67; Cullen et al.,1987, Nucleic Acids Research 15: 9163-9175; WO 00/24883). Isolation ofthe AMA1 gene and construction of plasmids or vectors comprising thegene can be accomplished according to the methods disclosed in WO00/24883.

More than one copy of a polynucleotide of the present invention may beinserted into the host cell to increase production of the gene product.An increase in the copy number of the polynucleotide can be obtained byintegrating at least one additional copy of the sequence into the hostcell genome or by including an amplifiable selectable marker gene withthe polynucleotide where cells containing amplified copies of theselectable marker gene, and thereby additional copies of thepolynucleotide, can be selected for by cultivating the cells in thepresence of the appropriate selectable agent.

The procedures used to ligate the elements described above to constructthe recombinant expression vectors of the present invention are wellknown to one skilled in the art (see, e.g., Sambrook et al., 1989,supra).

Host Cells

The present invention also relates to recombinant host cells, comprisinga polynucleotide of the present invention, which are advantageously usedin the recombinant production of the polypeptides. A vector comprising apolynucleotide of the present invention is introduced into a host cellso that the vector is maintained as a chromosomal integrant or as aself-replicating extra-chromosomal vector as described earlier. The term“host cell” encompasses any progeny of a parent cell that is notidentical to the parent cell due to mutations that occur duringreplication. The choice of a host cell will to a large extent dependupon the gene encoding the polypeptide and its source.

The host cell may be a unicellular microorganism, e.g., a prokaryote, ora non-unicellular microorganism, e.g., a eukaryote.

The host cell may also be a eukaryote, such as a mammalian, insect,plant, or fungal cell.

In a preferred aspect, the host cell is a fungal cell. “Fungi” as usedherein includes the phyla Ascomycota, Basidiomycota, Chytridiomycota,and Zygomycota (as defined by Hawksworth et al., In, Ainsworth andBisby's Dictionary of The Fungi, 8th edition, 1995, CAB International,University Press, Cambridge, UK) as well as the Oomycota (as cited inHawksworth et al., 1995, supra, page 171) and all mitosporic fungi(Hawksworth et al., 1995, supra).

In a more preferred aspect, the fungal host cell is a yeast cell.“Yeast” as used herein includes ascosporogenous yeast (Endomycetales),basidiosporogenous yeast, and yeast belonging to the Fungi Imperfecti(Blastomycetes). Since the classification of yeast may change in thefuture, for the purposes of this invention, yeast shall be defined asdescribed in Biology and Activities of Yeast (Skinner, F. A., Passmore,S. M., and Davenport, R. R., eds, Soc. App. Bacteriol. Symposium SeriesNo. 9, 1980).

In an even more preferred aspect, the yeast host cell is a Candida,Hansenula, Kluyveromyces, Pichia, Saccharomyces, Schizosaccharomyces, orYarrowia cell.

In a most preferred aspect, the yeast host cell is a Saccharomycescarlsbergensis, Saccharomyces cerevisiae, Saccharomyces diastaticus,Saccharomyces douglasii, Saccharomyces kluyveri, Saccharomyces norbensisor Saccharomyces oviformis cell. In another most preferred aspect, theyeast host cell is a Kluyveromyces lactis cell. In another mostpreferred aspect, the yeast host cell is a Yarrowia lipolytica cell.

In another more preferred aspect, the fungal host cell is a filamentousfungal cell. “Filamentous fungi” include all filamentous forms of thesubdivision Eumycota and Oomycota (as defined by Hawksworth et al.,1995, supra). The filamentous fungi are generally characterized by amycelial wall composed of chitin, cellulose, glucan, chitosan, mannan,and other complex polysaccharides. Vegetative growth is by hyphalelongation and carbon catabolism is obligately aerobic. In contrast,vegetative growth by yeasts such as Saccharomyces cerevisiae is bybudding of a unicellular thallus and carbon catabolism may befermentative.

In an even more preferred aspect, the filamentous fungal host cell is anAcremonium, Aspergillus, Aureobasidium, Bjerkandera, Ceriporiopsis,Coprinus, Coriolus, Cryptococcus, Filobasidium, Fusarium, Humicola,Magnaporthe, Mucor, Myceliophthora, Neocallimastix, Neurospora,Paecilomyces, Penicillium, Phanerochaete, Phlebia, Piromyces, Pleurotus,Schizophyllum, Talaromyces, Thermoascus, Thielavia, Tolypocladium,Trametes, or Trichoderma cell.

In a most preferred aspect, the filamentous fungal host cell is anAspergillus awamori, Aspergillus fumigatus, Aspergillus foetidus,Aspergillus japonicus, Aspergillus nidulans, Aspergillus niger orAspergillus oryzae cell. In another most preferred aspect, thefilamentous fungal host cell is a Fusarium bactridioides, Fusariumcerealis, Fusarium crookwellense, Fusarium culmorum, Fusariumgraminearum, Fusarium graminum, Fusarium heterosporum, Fusarium negundi,Fusarium oxysporum, Fusarium reticulatum, Fusarium roseum, Fusariumsambucinum, Fusarium sarcochroum, Fusarium sporotrichioides, Fusariumsulphureum, Fusarium torulosum, Fusarium trichothecioides, or Fusariumvenenatum cell. In another most preferred aspect, the filamentous fungalhost cell is a Bjerkandera adusta, Ceriporiopsis aneirina, Ceriporiopsisaneirina, Ceriporiopsis caregiea, Ceriporiopsis gilvescens,Ceriporiopsis pannocinta, Ceriporiopsis rivulosa, Ceriporiopsis subrufa,or Ceriporiopsis subvermispora, Coprinus cinereus, Coriolus hirsutus,Humicola insolens, Humicola lanuginosa, Mucor miehei, Myceliophthorathermophila, Neurospora crassa, Penicillium purpurogenum, Phanerochaetechrysosporium, Phlebia radiata, Pleurotus eryngii, Thielavia terrestris,Trametes villosa, Trametes versicolor, Trichoderma harzianum,Trichoderma koningii, Trichoderma longibrachiatum, Trichoderma reesei,or Trichoderma viride cell.

Fungal cells may be transformed by a process involving protoplastformation, transformation of the protoplasts, and regeneration of thecell wall in a manner known per se. Suitable procedures fortransformation of Aspergillus and Trichoderma host cells are describedin EP 238 023 and Yelton et al., 1984, Proceedings of the NationalAcademy of Sciences USA 81: 1470-1474. Suitable methods for transformingFusarium species are described by Malardier et al., 1989, Gene 78:147-156, and WO 96/00787. Yeast may be transformed using the proceduresdescribed by Becker and Guarente, In Abelson, J. N. and Simon, M. I.,editors, Guide to Yeast Genetics and Molecular Biology, Methods inEnzymology, Volume 194, pp 182-187, Academic Press, Inc., New York; Itoet al., 1983, Journal of Bacteriology 153: 163; and Hinnen et al., 1978,Proceedings of the National Academy of Sciences USA 75: 1920.

Methods of Production

The present invention also relates to methods for producing apolypeptide of the present invention, comprising (a) cultivating a cell,which in its wild-type form is capable of producing the polypeptide,under conditions conducive for production of the polypeptide; and (b)recovering the polypeptide. Preferably, the cell is of the genusAspergillus, and more preferably Aspergillus niger or Aspergillusoryzae.

The present invention also relates to methods for producing apolypeptide of the present invention, comprising (a) cultivating a hostcell under conditions conducive for production of the polypeptide; and(b) recovering the polypeptide.

The present invention also relates to methods for producing apolypeptide of the present invention, comprising (a) cultivating a hostcell under conditions conducive for production of the polypeptide,wherein the host cell comprises a mutant nucleotide sequence having atleast one mutation in the mature polypeptide coding region of SEQ ID NO:4, wherein the mutant nucleotide sequence encodes a polypeptide whichconsists of amino acids 2 to 148 of SEQ ID NO: 5, and (b) recovering thepolypeptide.

In the production methods of the present invention, the cells arecultivated in a nutrient medium suitable for production of thepolypeptide using methods well known in the art. For example, the cellmay be cultivated by shake flask cultivation, and small-scale orlarge-scale fermentation (including continuous, batch, fed-batch, orsolid state fermentations) in laboratory or industrial fermentorsperformed in a suitable medium and under conditions allowing thepolypeptide to be expressed and/or isolated. The cultivation takes placein a suitable nutrient medium comprising carbon and nitrogen sources andinorganic salts, using procedures known in the art. Suitable media areavailable from commercial suppliers or may be prepared according topublished compositions (e.g., in catalogues of the American Type CultureCollection). If the polypeptide is secreted into the nutrient medium,the polypeptide can be recovered directly from the medium. If thepolypeptide is not secreted, it can be recovered from cell lysates.

The polypeptides may be detected using methods known in the art that arespecific for the polypeptides. These detection methods may include useof specific antibodies, formation of an enzyme product, or disappearanceof an enzyme substrate. For example, an enzyme assay may be used todetermine the activity of the polypeptide as described herein.

The resulting polypeptide may be recovered using methods known in theart. For example, the polypeptide may be recovered from the nutrientmedium by conventional procedures including, but not limited to,centrifugation, filtration, extraction, spray-drying, evaporation, orprecipitation.

The polypeptides of the present invention may be purified by a varietyof procedures known in the art including, but not limited to,chromatography (e.g., ion exchange, affinity, hydrophobic,chromatofocusing, and size exclusion), electrophoretic procedures (e.g.,preparative isoelectric focusing), differential solubility (e.g.,ammonium sulfate precipitation), SDS-PAGE, or extraction (see, e.g.,Protein Purification, J.-C. Janson and Lars Ryden, editors, VCHPublishers, New York, 1989).

Plants

The present invention also relates to a transgenic plant, plant part, orplant cell which has been transformed with a nucleotide sequenceencoding a polypeptide having protease activity of the present inventionso as to express and produce the polypeptide in recoverable quantities.The polypeptide may be recovered from the plant or plant part.Alternatively, the plant or plant part containing the recombinantpolypeptide may be used as such for improving the quality of a food orfeed, e.g., improving nutritional value, palatability, and rheologicalproperties, or to destroy an antinutritive factor.

The transgenic plant can be dicotyledonous (a dicot) or monocotyledonous(a monocot). Examples of monocot plants are grasses, such as meadowgrass (blue grass, Poa), forage grass such as Festuca, Lolium, temperategrass, such as Agrostis, and cereals, e.g., wheat, oats, rye, barley,rice, sorghum, and maize (corn).

Examples of dicot plants are tobacco, legumes, such as lupins, potato,sugar beet, pea, bean and soybean, and cruciferous plants (familyBrassicaceae), such as cauliflower, rape seed, and the closely relatedmodel organism Arabidopsis thaliana.

Examples of plant parts are stem, callus, leaves, root, fruits, seeds,and tubers as well as the individual tissues comprising these parts,e.g., epidermis, mesophyll, parenchyme, vascular tissues, meristems.Specific plant cell compartments, such as chloroplasts, apoplasts,mitochondria, vacuoles, peroxisomes and cytoplasm are also considered tobe a plant part. Furthermore, any plant cell, whatever the tissueorigin, is considered to be a plant part. Likewise, plant parts such asspecific tissues and cells isolated to facilitate the utilisation of theinvention are also considered plant parts, e.g., embryos, endosperms,aleurone and seeds coats.

Also included within the scope of the present invention are the progenyof such plants, plant parts, and plant cells.

The transgenic plant or plant cell expressing a polypeptide of thepresent invention may be constructed in accordance with methods known inthe art. In short, the plant or plant cell is constructed byincorporating one or more expression constructs encoding a polypeptideof the present invention into the plant host genome and propagating theresulting modified plant or plant cell into a transgenic plant or plantcell.

The expression construct is conveniently a nucleic acid construct whichcomprises a polynucleotide encoding a polypeptide of the presentinvention operably linked with appropriate regulatory sequences requiredfor expression of the nucleotide sequence in the plant or plant part ofchoice. Furthermore, the expression construct may comprise a selectablemarker useful for identifying host cells into which the expressionconstruct has been integrated and DNA sequences necessary forintroduction of the construct into the plant in question (the latterdepends on the DNA introduction method to be used).

The choice of regulatory sequences, such as promoter and terminatorsequences and optionally signal or transit sequences is determined, forexample, on the basis of when, where, and how the polypeptide is desiredto be expressed. For instance, the expression of the gene encoding apolypeptide of the present invention may be constitutive or inducible,or may be developmental, stage or tissue specific, and the gene productmay be targeted to a specific tissue or plant part such as seeds orleaves. Regulatory sequences are, for example, described by Tague etal., 1988, Plant Physiology 86: 506.

For constitutive expression, the 35S-CaMV, the maize ubiquitin 1, andthe rice actin 1 promoter may be used (Franck et al., 1980, Cell 21:285-294, Christensen et al., 1992, Plant Mo. Biol. 18: 675-689; Zhang etal., 1991, Plant Cell 3: 1155-1165). Organ-specific promoters may be,for example, a promoter from storage sink tissues such as seeds, potatotubers, and fruits (Edwards & Coruzzi, 1990, Ann. Rev. Genet. 24:275-303), or from metabolic sink tissues such as meristems (Ito et al.,1994, Plant Mol. Biol. 24: 863-878), a seed specific promoter such asthe glutelin, prolamin, globulin, or albumin promoter from rice (Wu etal., 1998, Plant and Cell Physiology 39: 885-889), a Vicia faba promoterfrom the legumin B4 and the unknown seed protein gene from Vicia faba(Conrad et al., 1998, Journal of Plant Physiology 152: 708-711), apromoter from a seed oil body protein (Chen et al., 1998, Plant and CellPhysiology 39: 935-941), the storage protein napA promoter from Brassicanapus, or any other seed specific promoter known in the art, e.g., asdescribed in WO 91/14772. Furthermore, the promoter may be a leafspecific promoter such as the rbcs promoter from rice or tomato (Kyozukaet al., 1993, Plant Physiology 102: 991-1000, the chlorella virusadenine methyltransferase gene promoter (Mitra and Higgins, 1994, PlantMolecular Biology 26: 85-93), or the aldP gene promoter from rice(Kagaya et al., 1995, Molecular and General Genetics 248: 668-674), or awound inducible promoter such as the potato pin2 promoter (Xu et al.,1993, Plant Molecular Biology 22: 573-588). Likewise, the promoter mayinducible by abiotic treatments such as temperature, drought, oralterations in salinity or induced by exogenously applied substancesthat activate the promoter, e.g., ethanol, oestrogens, plant hormonessuch as ethylene, abscisic acid, and gibberellic acid, and heavy metals.

A promoter enhancer element may also be used to achieve higherexpression of a polypeptide of the present invention in the plant. Forinstance, the promoter enhancer element may be an intron which is placedbetween the promoter and the nucleotide sequence encoding a polypeptideof the present invention. For instance, Xu et al., 1993, supra, disclosethe use of the first intron of the rice actin 1 gene to enhanceexpression.

The selectable marker gene and any other parts of the expressionconstruct may be chosen from those available in the art.

The nucleic acid construct is incorporated into the plant genomeaccording to conventional techniques known in the art, includingAgrobacterium-mediated transformation, virus-mediated transformation,microinjection, particle bombardment, biolistic transformation, andelectroporation (Gasser et al., 1990, Science 244: 1293; Potrykus, 1990,Bio/Technology 8: 535; Shimamoto et al., 1989, Nature 338: 274).

Presently, Agrobacterium tumefaciens-mediated gene transfer is themethod of choice for generating transgenic dicots (for a review, seeHooykas and Schilperoort, 1992, Plant Molecular Biology 19: 15-38) andcan also be used for transforming monocots, although othertransformation methods are often used for these plants. Presently, themethod of choice for generating transgenic monocots is particlebombardment (microscopic gold or tungsten particles coated with thetransforming DNA) of embryonic calli or developing embryos (Christou,1992, Plant Journal 2: 275-281; Shimamoto, 1994, Current OpinionBiotechnology 5: 158-162; Vasil et al., 1992, Bio/Technology 10:667-674). An alternative method for transformation of monocots is basedon protoplast transformation as described by Omirulleh et al., 1993,Plant Molecular Biology 21: 415-428.

Following transformation, the transformants having incorporated theexpression construct are selected and regenerated into whole plantsaccording to methods well-known in the art. Often the transformationprocedure is designed for the selective elimination of selection geneseither during regeneration or in the following generations by using, forexample, co-transformation with two separate T-DNA constructs or sitespecific excision of the selection gene by a specific recombinase.

The present invention also relates to methods for producing apolypeptide of the present invention comprising (a) cultivating atransgenic plant or a plant cell comprising a polynucleotide encoding apolypeptide having protease activity of the present invention underconditions conducive for production of the polypeptide; and (b)recovering the polypeptide.

Removal or Reduction of Protease Activity

The present invention also relates to methods for producing a mutant ofa parent cell, which comprises disrupting or deleting a polynucleotidesequence, or a portion thereof, encoding a polypeptide of the presentinvention, which results in the mutant cell producing less of thepolypeptide than the parent cell when cultivated under the sameconditions.

The mutant cell may be constructed by reducing or eliminating expressionof a nucleotide sequence encoding a polypeptide of the present inventionusing methods well known in the art, for example, insertions,disruptions, replacements, or deletions. The nucleotide sequence to bemodified or inactivated may be, for example, the coding region or a partthereof essential for activity, or a regulatory element required for theexpression of the coding region. An example of such a regulatory orcontrol sequence may be a promoter sequence or a functional partthereof, i.e., a part that is sufficient for affecting expression of thenucleotide sequence. Other control sequences for possible modificationinclude, but are not limited to, a leader, polyadenylation sequence,propeptide sequence, signal peptide sequence, transcription terminator,and transcriptional activator.

Modification or inactivation of the nucleotide sequence may be performedby subjecting the parent cell to mutagenesis and selecting for mutantcells in which expression of the nucleotide sequence has been reduced oreliminated. The mutagenesis, which may be specific or random, may beperformed, for example, by use of a suitable physical or chemicalmutagenizing agent, by use of a suitable oligonucleotide, or bysubjecting the DNA sequence to PCR generated mutagenesis. Furthermore,the mutagenesis may be performed by use of any combination of thesemutagenizing agents.

Examples of a physical or chemical mutagenizing agent suitable for thepresent purpose include ultraviolet (UV) irradiation, hydroxylamine,N-methyl-N′-nitro-N-nitrosoguanidine (MNNG), O-methyl hydroxylamine,nitrous acid, ethyl methane sulphonate (EMS), sodium bisulphite, formicacid, and nucleotide analogues.

When such agents are used, the mutagenesis is typically performed byincubating the parent cell to be mutagenized in the presence of themutagenizing agent of choice under suitable conditions, and screeningand/or selecting for mutant cells exhibiting reduced or no expression ofthe gene.

Modification or inactivation of the nucleotide sequence may beaccomplished by introduction, substitution, or removal of one or morenucleotides in the gene or a regulatory element required for thetranscription or translation thereof. For example, nucleotides may beinserted or removed so as to result in the introduction of a stop codon,the removal of the start codon, or a change in the open reading frame.Such modification or inactivation may be accomplished by site-directedmutagenesis or PCR generated mutagenesis in accordance with methodsknown in the art. Although, in principle, the modification may beperformed in vivo, i.e., directly on the cell expressing the nucleotidesequence to be modified, it is preferred that the modification beperformed in vitro as exemplified below.

An example of a convenient way to eliminate or reduce expression of anucleotide sequence by a cell is based on techniques of genereplacement, gene deletion, or gene disruption. For example, in the genedisruption method, a nucleic acid sequence corresponding to theendogenous nucleotide sequence is mutagenized in vitro to produce adefective nucleic acid sequence which is then transformed into theparent cell to produce a defective gene. By homologous recombination,the defective nucleic acid sequence replaces the endogenous nucleotidesequence. It may be desirable that the defective nucleotide sequencealso encodes a marker that may be used for selection of transformants inwhich the nucleotide sequence has been modified or destroyed. In aparticularly preferred embodiment, the nucleotide sequence is disruptedwith a selectable marker such as those described herein.

Alternatively, modification or inactivation of the nucleotide sequencemay be performed by established anti-sense techniques using a sequencecomplementary to the nucleotide sequence. More specifically, expressionof the nucleotide sequence by a cell may be reduced or eliminated byintroducing a sequence complementary to the nucleotide sequence of thegene that may be transcribed in the cell and is capable of hybridizingto the mRNA produced in the cell. Under conditions allowing thecomplementary anti-sense nucleotide sequence to hybridize to the mRNA,the amount of protein translated is thus reduced or eliminated.

The present invention further relates to a mutant cell of a parent cellwhich comprises a disruption or deletion of a nucleotide sequenceencoding the polypeptide or a control sequence thereof, which results inthe mutant cell producing less of the polypeptide than the parent cell.

The polypeptide-deficient mutant cells so created are particularlyuseful as host cells for the expression of homologous and/orheterologous polypeptides. It has been found that a higher yield ofhomologous and/or heterologous polypeptides expressed in a host celldeficient for the protease according to the invention may be obtained,compared to the corresponding yield in same host cell but having normallevel of the protease of the invention. Therefore, the present inventionfurther relates to methods for producing a homologous or heterologouspolypeptide comprising (a) cultivating the mutant cell under conditionsconducive for production of the polypeptide; and (b) recovering thepolypeptide. The term “heterologous polypeptides” is defined herein aspolypeptides which are not native to the host cell, a native protein inwhich modifications have been made to alter the native sequence, or anative protein whose expression is quantitatively altered as a result ofa manipulation of the host cell by recombinant DNA techniques.

It has been found that the polypeptide of the invention is responsiblefor cleaving off the CBM (Carbohydrate binding Module) of at least somepolypeptides comprising two or more domains of which one domain is theCBM. Thus, in a further aspect the present invention relates to a methodfor producing a protein product comprising a polypeptide comprising twoor more domains of which one domain is a CBM by fermentation of a cellhaving reduced expression of the polypeptide of the invention, whichcell produces said polypeptide comprising two or more domains, andrecovering the produce from the fermentation broth, and optionallysubjecting the recovered product to further purification.

In a further aspect, the present invention relates to a method forproducing a protein product essentially free of the protease activity ofthe polypeptide of the invention by fermentation of a cell whichproduces both a polypeptide of the present invention as well as theprotein product of interest by adding an effective amount of an agentcapable of inhibiting the protease activity of the polypeptide of theinvention to the fermentation broth before, during, or after thefermentation has been completed, recovering the product of interest fromthe fermentation broth, and optionally subjecting the recovered productto further purification.

In a further aspect, the present invention relates to a method forproducing a protein product essentially free of the protease activity ofthe polypeptide of the invention by cultivating the cell underconditions permitting the expression of the product, subjecting theresultant culture broth to a combined pH and temperature treatment so asto reduce the protease activity of the polypeptide of the inventionsubstantially, and recovering the product from the culture broth.Alternatively, the combined pH and temperature treatment may beperformed on an enzyme preparation recovered from the culture broth. Thecombined pH and temperature treatment may optionally be used incombination with a treatment with a protease inhibitor.

In accordance with this aspect of the invention, it is possible toremove at least 60%, preferably at least 65%, preferably at least 70%,preferably at least 75%, preferably at least 80%, preferably at least85%, preferably at least 90%, preferably at least 95%, preferably atleast 96%, more preferably at least 97%, even more preferably at least98% and most preferably at least 99% of the protease activity of thepolypeptide of the invention.

The methods used for cultivation and purification of the product ofinterest may be performed by methods known in the art.

The methods of the present invention for producing an essentiallyprotease-free product or a product comprising a polypeptide comprisingtwo or more domains of which one domain is a CBM wherein the amount ofsaid polypeptide without the CBM is considerably low is of particularinterest in the production of eukaryotic polypeptides, in particularfungal proteins such as enzymes. The enzyme may be selected from, e.g.,an amylolytic enzyme, lipolytic enzyme, proteolytic enzyme, cellulyticenzyme, oxidoreductase, or plant cell-wall degrading enzyme. Examples ofsuch enzymes include an aminopeptidase, amylase, amyloglucosidase,carbohydrase, carboxypeptidase, catalase, cellulase, chitinase,cutinase, cyclodextrin glycosyltransferase, deoxyribonuclease, esterase,galactosidase, beta-galactosidase, glucoamylase, glucose oxidase,glucosidase, haloperoxidase, hemicellulase, invertase, isomerase,laccase, ligase, lipase, lyase, mannosidase, oxidase, pectinolyticenzyme, peroxidase, phytase, phenoloxidase, polyphenoloxidase,proteolytic enzyme, ribonuclease, transferase, transglutaminase, orxylanase. The protease-deficient cells may also be used to expressheterologous proteins of pharmaceutical interest such as hormones,growth factors, receptors, and the like.

It will be understood that the term “eukaryotic polypeptides” includesnot only native polypeptides, but also those polypeptides, e.g.,enzymes, which have been modified by amino acid substitutions, deletionsor additions, or other such modifications to enhance activity,thermostability, pH tolerance and the like.

In a further aspect, the present invention relates to a protein productessentially free from protease activity which is produced by a method ofthe present invention.

Compositions

The present invention also relates to compositions comprising apolypeptide of the present invention. Preferably, the compositions areenriched in such a polypeptide. The term “enriched” indicates that theprotease activity of the composition has been increased, e.g., with anenrichment factor of 1.1.

The composition may comprise a polypeptide of the present invention asthe major enzymatic component, e.g., a mono-component composition.Alternatively, the composition may comprise multiple enzymaticactivities, such as an aminopeptidase, amylase, carbohydrase,carboxypeptidase, catalase, cellulase, chitinase, cutinase, cyclodextringlycosyltransferase, deoxyribonuclease, esterase, alpha-galactosidase,beta-galactosidase, glucoamylase, alpha-glucosidase, beta-glucosidase,haloperoxidase, invertase, laccase, lipase, mannosidase, oxidase,pectinolytic enzyme, peptidoglutaminase, peroxidase, phytase,polyphenoloxidase, proteolytic enzyme, ribonuclease, transglutaminase,or xylanase. The additional enzyme(s) may be produced, for example, by amicroorganism belonging to the genus Aspergillus, preferably Aspergillusaculeatus, Aspergillus awamori, Aspergillus fumigatus, Aspergillusfoetidus, Aspergillus japonicus, Aspergillus nidulans, Aspergillusniger, or Aspergillus oryzae; Fusarium, preferably Fusariumbactridioides, Fusarium cerealis, Fusarium crookwellense, Fusariumculmorum, Fusarium graminearum, Fusarium graminum, Fusariumheterosporum, Fusarium negundi, Fusarium oxysporum, Fusariumreticulatum, Fusarium roseum, Fusarium sambucinum, Fusarium sarcochroum,Fusarium sulphureum, Fusarium toruloseum, Fusarium trichothecioides, orFusarium venenatum; Humicola, preferably Humicola insolens or Humicolalanuginosa; or Trichoderma, preferably Trichoderma harzianum,Trichoderma koningii, Trichoderma longibrachiatum, Trichoderma reesei,or Trichoderma viride.

The polypeptide compositions may be prepared in accordance with methodsknown in the art and may be in the form of a liquid or a drycomposition. For instance, the polypeptide composition may be in theform of a granulate or a microgranulate. The polypeptide to be includedin the composition may be stabilized in accordance with methods known inthe art.

Examples are given below of preferred uses of the polypeptidecompositions of the invention. The dosage of the polypeptide compositionof the invention and other conditions under which the composition isused may be determined on the basis of methods known in the art.

Uses

The present invention is also directed to methods for using thepolypeptides having protease activity.

Detergent Compositions

The enzyme of the invention may be added to and thus become a componentof a detergent composition.

The detergent composition of the invention may for example be formulatedas a hand or machine laundry detergent composition including a laundryadditive composition suitable for pre-treatment of stained fabrics and arinse added fabric softener composition, or be formulated as a detergentcomposition for use in general household hard surface cleaningoperations, or be formulated for hand or machine dishwashing operations.

In a specific aspect, the invention provides a detergent additivecomprising the enzyme of the invention. The detergent additive as wellas the detergent composition may comprise one or more other enzymes suchas a protease, a lipase, a cutinase, an amylase, a carbohydrase, acellulase, a pectinase, a mannanase, an arabinase, a galactanase, axylanase, an oxidase, e.g., a laccase, and/or a peroxidase.

In general the properties of the chosen enzyme(s) should be compatiblewith the selected detergent, (i.e. pH-optimum, compatibility with otherenzymatic and non-enzymatic ingredients, etc.), and the enzyme(s) shouldbe present in effective amounts.

Proteases: Suitable proteases include those of animal, vegetable ormicrobial origin. Microbial origin is preferred. Chemically modified orprotein engineered mutants are included. The protease may be a serineprotease or a metallo protease, preferably an alkaline microbialprotease or a trypsin-like protease. Examples of alkaline proteases aresubtilisins, especially those derived from Bacillus, e.g., subtilisinNovo, subtilisin Carlsberg, subtilisin 309, subtilisin 147 andsubtilisin 168 (described in WO 89/06279). Examples of trypsin-likeproteases are trypsin (e.g. of porcine or bovine origin) and theFusarium protease described in WO 89/06270 and WO 94/25583.

Examples of useful proteases are the variants described in WO 92/19729,WO 98/20115, WO 98/20116, and WO 98/34946, especially the variants withsubstitutions in one or more of the following positions: 27, 36, 57, 76,87, 97, 101, 104, 120, 123, 167, 170, 194, 206, 218, 222, 224, 235 and274—make references to specific sequences and positions.

Preferred commercially available protease enzymes include Alcalase™,Savinase™, Primase™, Duralase™, Esperase™, and Kannase™ (Novozymes A/S),Maxatase™, Maxacal™, Maxapem™, Properase™, Purafect™, Purafect OxP™,FN2™, and FN3™ (Genencor International Inc.).

Lipases: Suitable lipases include those of bacterial or fungal origin.Chemically modified or protein engineered mutants are included. Examplesof useful lipases include lipases from Humicola (synonym Thermomyces),e.g. from H. lanuginosa (T. lanuginosus) as described in EP 258 068 andEP 305 216 or from H. insolens as described in WO 96/13580, aPseudomonas lipase, e.g. from P. alcaligenes or P. pseudoalcaligenes (EP218 272), P. cepacia (EP 331 376), P. stutzeri (GB 1,372,034), P.fluorescens, Pseudomonas sp. strain SD 705 (WO 95/06720 and WO96/27002), P. wisconsinensis (WO 96/12012), a Bacillus lipase, e.g. fromB. subtilis (Dartois et al. (1993), Biochemica et Biophysica Acta, 1131,253-360), B. stearothermophilus (JP 64/744992) or B. pumilus (WO91/16422).

Other examples are lipase variants such as those described in WO92/05249, WO 94/01541, EP 407 225, EP 260 105, WO 95/35381, WO 96/00292,WO 95/30744, WO 94/25578, WO 95/14783, WO 95/22615, WO 97/04079 and WO97/07202.

Preferred commercially available lipase enzymes include Lipolase™ andLipolase Ultra™ (Novozymes A/S).

Amylases: Suitable amylases (α and/or β) include those of bacterial orfungal origin. Chemically modified or protein engineered mutants areincluded. Amylases include, for example, α-amylases obtained fromBacillus, e.g. a special strain of B. licheniformis, described in moredetail in GB 1,296,839.

Examples of useful amylases are the variants described in WO 94/02597,WO 94/18314, WO 96/23873, and WO 97/43424, especially the variants withsubstitutions in one or more of the following positions: 15, 23, 105,106, 124, 128, 133, 154, 156, 181, 188, 190, 197, 202, 208, 209, 243,264, 304, 305, 391, 408, and 444—make references to specific sequencesand positions.

Commercially available amylases are Duramyl™, Termamyl™, Fungamyl™ andBAN™ (Novozymes A/S), Rapidase™ and Purastar™ (from GenencorInternational Inc.).

Cellulases: Suitable cellulases include those of bacterial or fungalorigin. Chemically modified or protein engineered mutants are included.Suitable cellulases include cellulases from the genera Bacillus,Pseudomonas, Humicola, Fusarium, Thielavia, Acremonium, e.g. the fungalcellulases produced from Humicola insolens, Myceliophthora thermophilaand Fusarium oxysporum disclosed in U.S. Pat. No. 4,435,307, U.S. Pat.No. 5,648,263, U.S. Pat. No. 5,691,178, U.S. Pat. No. 5,776,757 and WO89/09259.

Especially suitable cellulases are the alkaline or neutral cellulaseshaving colour care benefits. Examples of such cellulases are cellulasesdescribed in EP 0 495 257, EP 0 531 372, WO 96/11262, WO 96/29397, WO98/08940. Other examples are cellulase variants such as those describedin WO 94/07998, EP 0 531 315, U.S. Pat. No. 5,457,046, U.S. Pat. No.5,686,593, U.S. Pat. No. 5,763,254, WO 95/24471, WO 98/12307 and WO1999/001544.

Commercially available cellulases include Celluzyme™, and Carezyme™(Novozymes A/S), Clazinase™, and Puradax HA™ (Genencor InternationalInc.), and KAC-500(B)™ (Kao Corporation).

Peroxidases/Oxidases: Suitable peroxidases/oxidases include those ofplant, bacterial or fungal origin. Chemically modified or proteinengineered mutants are included. Examples of useful peroxidases includeperoxidases from Coprinus, e.g. from C. cinereus, and variants thereofas those described in WO 93/24618, WO 95/10602, and WO 98/15257.

Commercially available peroxidases include Guardzyme™ (Novozymes A/S).

The detergent enzyme(s) may be included in a detergent composition byadding separate additives containing one or more enzymes, or by adding acombined additive comprising all of these enzymes. A detergent additiveof the invention, i.e. a separate additive or a combined additive, canbe formulated e.g. as a granulate, a liquid, a slurry, etc. Preferreddetergent additive formulations are granulates, in particularnon-dusting granulates, liquids, in particular stabilized liquids, orslurries.

Non-dusting granulates may be produced, e.g., as disclosed in U.S. Pat.Nos. 4,106,991 and 4,661,452 and may optionally be coated by methodsknown in the art. Examples of waxy coating materials are poly(ethyleneoxide) products (polyethyleneglycol, PEG) with mean molar weights of1000 to 20000; ethoxylated nonylphenols having from 16 to 50 ethyleneoxide units; ethoxylated fatty alcohols in which the alcohol containsfrom 12 to 20 carbon atoms and in which there are 15 to 80 ethyleneoxide units; fatty alcohols; fatty acids; and mono- and di- andtriglycerides of fatty acids. Examples of film-forming coating materialssuitable for application by fluid bed techniques are given in GB1483591. Liquid enzyme preparations may, for instance, be stabilized byadding a polyol such as propylene glycol, a sugar or sugar alcohol,lactic acid or boric acid according to established methods. Protectedenzymes may be prepared according to the method disclosed in EP 238,216.

The detergent composition of the invention may be in any convenientform, e.g., a bar, a tablet, a powder, a granule, a paste or a liquid. Aliquid detergent may be aqueous, typically containing up to 70% waterand 0-30% organic solvent, or non-aqueous.

The detergent composition comprises one or more surfactants, which maybe non-ionic including semi-polar and/or anionic and/or cationic and/orzwitterionic. The surfactants are typically present at a level of from0.1% to 60% by weight.

When included therein the detergent will usually contain from about 1%to about 40% of an anionic surfactant such as linearalkylbenzenesulfonate, alpha-olefinsulfonate, alkyl sulfate (fattyalcohol sulfate), alcohol ethoxysulfate, secondary alkanesulfonate,alpha-sulfo fatty acid methyl ester, alkyl- or alkenylsuccinic acid orsoap.

When included therein the detergent will usually contain from about 0.2%to about 40% of a non-ionic surfactant such as alcohol ethoxylate,nonylphenol ethoxylate, alkylpolyglycoside, alkyldimethylamineoxide,ethoxylated fatty acid monoethanolamide, fatty acid monoethanolamide,polyhydroxy alkyl fatty acid amide, or N-acyl N-alkyl derivatives ofglucosamine (“glucamides”).

The detergent may contain 0-65% of a detergent builder or complexingagent such as zeolite, diphosphate, triphosphate, phosphonate,carbonate, citrate, nitrilotriacetic acid, ethylenediaminetetraaceticacid, diethylenetriaminepentaacetic acid, alkyl- or alkenylsuccinicacid, soluble silicates or layered silicates (e.g. SKS-6 from Hoechst).

The detergent may comprise one or more polymers. Examples arecarboxymethylcellulose, poly(vinylpyrrolidone), poly (ethylene glycol),poly(vinyl alcohol), poly(vinylpyridine-N-oxide), poly(vinylimidazole),polycarboxylates such as polyacrylates, maleic/acrylic acid copolymersand lauryl methacrylate/acrylic acid copolymers.

The detergent may contain a bleaching system which may comprise a H₂O₂source such as perborate or percarbonate which may be combined with aperacid-forming bleach activator such as tetraacetylethylenediamine ornonanoyloxybenzenesulfonate. Alternatively, the bleaching system maycomprise peroxyacids of e.g. the amide, imide, or sulfone type.

The enzyme(s) of the detergent composition of the invention may bestabilized using conventional stabilizing agents, e.g., a polyol such aspropylene glycol or glycerol, a sugar or sugar alcohol, lactic acid,boric acid, or a boric acid derivative, e.g., an aromatic borate ester,or a phenyl boronic acid derivative such as 4-formylphenyl boronic acid,and the composition may be formulated as described in e.g. WO 92/19709and WO 92/19708.

The detergent may also contain other conventional detergent ingredientssuch as e.g. fabric conditioners including clays, foam boosters, sudssuppressors, anti-corrosion agents, soil-suspending agents, anti-soilredeposition agents, dyes, bactericides, optical brighteners,hydrotropes, tarnish inhibitors, or perfumes.

It is at present contemplated that in the detergent compositions anyenzyme, in particular the enzyme of the invention, may be added in anamount corresponding to 0.01-100 mg of enzyme protein per liter of washliquor, preferably 0.05-5 mg of enzyme protein per liter of wash liquor,in particular 0.1-1 mg of enzyme protein per liter of wash liquor.

The enzyme of the invention may additionally be incorporated in thedetergent formulations disclosed in WO 97/07202 which is herebyincorporated as reference.

The present invention is further described by the following exampleswhich should not be construed as limiting the scope of the invention.

EXAMPLES

Chemicals used as buffers and substrates were commercial products of atleast reagent grade.

Media and Solutions

Methods

Unless otherwise stated, DNA manipulations and transformations wereperformed using standard methods of molecular biology as described inSambrook et al. (1989) Molecular cloning: A laboratory manual, ColdSpring Harbor lab., Cold Spring Harbor, N.Y.; Ausubel, F. M. et al.(eds.) “Current protocols in Molecular Biology”, John Wiley and Sons,1995; Harwood, C. R., and Cutting, S. M. (eds.) “Molecular BiologicalMethods for Bacillus”. John Wiley and Sons, 1990.

Enzymes

Enzymes for DNA manipulations (e.g. restriction endonucleases, ligasesetc.) are obtainable from New England Biolabs, Inc. and were usedaccording to the manufacturer's instructions.

Microbial Strains

E. coli DH5α (TOYOBO)

The used Aspergillus niger strain was a descendent from an originalisolate C40, isolated by Novozymes from a soil sample collected inCopenhagen, Denmark.

A. oryzae BECh-2 is described in WO 2006/069289 (Novozymes).

Media and Reagents

Cove: 342.3 g/L Sucrose, 20 ml/L COVE salt solution, 10 mM Acetamide, 30g/L noble agar.

Cove salt solution: per liter 26 g KCl, 26 g MgSO₄-7 aq, 76 g KH₂PO₄, 50ml Cove trace metals.

Cove trace metals: per liter 0.04 g NaB₄O₇-10 aq, 0.4 g CuSO₄-5 aq, 1.2g FeSO₄-7 aq, 0.7 g MnSO₄-aq, 0.7 g Na₂MoO₂-2 aq, 0.7 g ZnSO₄-7 aq.

YPG: 4 g/L Yeast extract, 1 g/L KH₂PO₄, 0.5 g/L MgSO₄-7 aq, 5 g/LGlucose, pH 6.0.

STC: 0.8 M Sorbitol, 25 mM Tris pH 8, 25 mM CaCl₂.

STPC: 40% PEG4000 in STC buffer.

Cove top agarose: 342.3 g/L Sucrose, 20 ml/L COVE salt solution, 10 mMAcetamide, 10 g/L low melt agarose.

MS-9: per liter 30 g soybean powder, 20 g glycerol, pH 6.0.

MDU-pH5: per liter 45 g maltose-1 aq, 7 g yeast extract, 12 g KH₂PO₄, 1g MgSO₄-7 aq, 2 g K₂SO₄, 0.5 ml AMG trace metal solution and 25 g2-morpholinoethanesulfonic acid, pH 5.0.

Example 1 Semi-Purification of A. niger 19 kDa Protease

Preparation of the Enzyme Sample

A. niger cells were freeze dried and kept at 4° C. 10 g of freeze driedcells were frozen by liquid N₂ and crushed by Ball Mill (stainlesssteel, volume 420 ml, Irie Syoukai Co. Ltd.), then homogenized byPhyscotron (Microtec Nichion Co. Ltd.) in liquid N₂. The homogenate wassuspended in 120 ml of 20 mM Tris-HCl, pH 7.5. After centrifugation, theprecipitate was re-suspended in 120 ml of the same buffer andcentrifuged again. Two supernatants were combined and filtered through amembrane filter (0.2 micrometer pore size). The filtrate wasdiafiltrated against the same buffer, resulting in 151.5 ml of crudeenzyme sample.

Preparation of the Bacitracin Affinity Gel

Reagent:

Epoxy-activated Sepharose 6B (Amersham Biosciences, 17-0480-01)

Coupling buffer (50 mM Na₂B₄O₇—HCl, pH9)

Bacitracin (Wako Pure Chemical Industry Ltd., 022-07701, Lot EWM1905)

Procedure:

15 g of Epoxy-activated Sepharose 6B were suspended and washed withMilli-Q water according to the manufacturer's instructions.

Then the gel was washed with 200 ml of coupling buffer and filtered on aglass filter.

The gel cake was transferred to a sealed bottle with 50 ml couplingbuffer.

2.5 g Bacitracin were dissolved in 50 ml of coupling buffer and mixedwith the gel.

The reaction mixture was shaken gently at 25° C. overnight.

Wash away excess ligand using coupling buffer.

Block remaining active groups by 0.1M ethanol amine, pH 9 for 5 hrs at25° C.

Wash with Coupling Buffer

Wash with 20 mM immidazole buffer, pH 6.5, containing 1 M NaCl and 25%iso-Propanol

Purification of Proteases from A. niger by Bacitracin Affinity Column

Column size: 22×100 mm

Flow rate: 4 ml/min

Fraction size: 8 ml/min

The column was pre-equilibrated with 20 mM Tris-HCl, pH 7.5. 150 ml ofcrude enzyme sample was applied to the column. The column was washedwith 170 ml of the same buffer, then 120 ml of the same buffercontaining 1M NaCl. Proteases bound to the column were eluted by 120 mMof 1 M NaCl, and 25% iso-Propanol in the Tris buffer. The fractions thatexhibit UV absorption were pooled and diafiltrated against the Tris-HClbuffer to remove NaCl and iso-Propanol. 56 ml of pooled fractions wereconcentrated to 0.6 ml by ultrafiltration.

SDS-PAGE

SDS-PAGE was performed in combination of Compact PAGE, AE7300 andpre-cast gel c-PAGEL, 12.5%, 76 mm (W)×70 mm (H) (ATTO Co.). Runningbuffer and SDS buffer were prepared by following ATTO's instructionmanual. After electrophoresis, the gel was stained by SYPRO Orangeprotein gel stain (Invitrogen Co.). For identification of proteaseactivity, 2-Mercaptoethanol was removed from SDS-buffer and boiling stepof the sample was skipped. The gel was over-laid by 1% skim milk and 2%agarose dissolved in 50 mM Tris-HCl, pH 7.5.

The SDS-PAGE Gel is Shown in FIG. 1

lane 1: LMW Marker (97, 66, 45, 30, 20, 14.4 kDa, GE Healthcare))

lane 2: Purified Proteases (Boiled)

lane 3: Purified Proteases (without boiling and 2-Mercaptoethanol)

Skim milk-agarose over lay

The patterns of SDS-PAGE with and without boiling samples were differed.The semi-purified sample was applied to an N-terminal sequencinganalysis.

Example 2 De Novo Protein Sequencing

Partial amino acid sequence of the 19 kDa protease was obtained byN-terminal sequencing. For sample preparation a sample, semi-purifiedusing the Bacitracin affinity column, was precipitated with TCA,separated on SDS-PAGE and blotted to a PVDF membrane. For N-terminalamino acid sequencing a piece of the PVDF membrane loaded with the 19kDa band was cut out and placed in the blotting cartridge of an AppliedBiosystems Procise protein sequencer. The N-terminal sequencing wascarried out using the method run file for PVDF membrane samples (Pulsedliquid PVDF), in accordance with the manufacturer instructions. Thefollowing N-terminal sequence was obtained (one-letter code):

SPIPSYSRPGRG (SEQ ID NO: 1)

Example 3 Cloning and Sequencing of A. niger 19 kDa Protease Gene

Based on the partial amino acid sequences and molecular weightidentified by SDS-PAGE, the database search (JGI A. niger genomebrowser) was conducted and the following hit was obtained.

erseqn:zy163155 XSCFFLD1. Aspergillus niger genomic sequence Length= 3970925 Score = 30.0 bits (66), Expect = 0.98 Identities = 12/12(100%), Positives = 12/12 (100%) Frame = +1 Query: 1 SPIPSYSRPGRG 12SPIPSYSRPGRG Sbjct: 3509032 SPIPSYSRPGRG 350906

The following primers HU941 and HU942 which introduce a BamHI and anXhoI site, respectively, were designed based on the nucleotide sequencesinformation of the A. niger genome database.

HU941: TTTGGATCCACCATGTCCCCAATCCCCAGC (SEQ ID NO: 2) HU942:TTTCTCGAGTCACCCCAAGAAAACATCCAC (SEQ ID NO: 3)

A PCR reaction with the genome DNA of the Aspergillus niger strain astemplate was performed with an Expand™ PCR system (Roche Diagnostics,Japan) using HU941 and HU942. The amplification reactions (50 μl) werecomposed of 1 ng of template DNA per μl, 250 mM dNTP each, 250 nM primerHU941, 250 nM primer HU942, 0.1 U of Taq polymerase per μl in 1× buffer(Roche Diagnostics, Japan). The reactions were incubated in a DNA EnginePTC-200 (MJ-Research, Japan) programmed as follows: 1 cycle at 94° C.for 2 minutes; 30 cycles each at 92° C. for 1 minute, 55° C. for 1minute, and 72° C. for 1 minute; 1 cycle at 72° C. for 10 minutes; and ahold at 4° C.

The reaction products were isolated on a 1.0% agarose gel using TAEbuffer where a 0.5 kb product band was excised from the gel and purifiedusing a QIAquick™ Gel Extraction Kit (QIAGEN Inc., Valencia, Calif.)according to the manufacturer's instructions.

The 0.5 kb amplified DNA fragment was digested with BamHI and XhoI, andligated into the Aspergillus expression cassette pCaHj483 digested withBamH I and XhoI. The ligation mixture was transformed into E. coli DH5α(TOYOBO) to create the expression plasmid pHUda772. The amplifiedplasmid was recovered using a QIAprep® Spin Miniprep kit (QIAGEN Inc.,Valencia, Calif.) according to the manufacturer's instructions.

Plasmid pCaHj483 comprised an expression cassette based on theAspergillus niger neutral amylase II promoter fused to the Aspergillusnidulans triose phosphate isomerase non translated leader sequence(Na2/tpi promoter) and the Aspergillus niger amyloglycosidase terminator(AMG terminator), the selective marker amdS from Aspergillus nidulansenabling growth on acetamide as sole nitrogen source.

The resultant plasmid was sequenced and compared to the Aspergillusniger genome database, showing that clones encode the unknown 19 kDaprotease. The cloned DNA sequences and its deduced amino acid sequencesby predicting the introns (by NetGene 2) and results of the homologysearch based on the amino acid sequences.

The sequence of the Aspergillus niger 19 kDa gene and deduced amino acidsequence is shown in FIG. 2.

Results of the Homology Search

Database: uniprot_trembl Program: blastp Id E Description a2q7n9 5e−82Similarity to hypothetical protein encoded by slr0318 - Synechocystissp. q2u3f4 5e−35 Predicted protein. a2qz06 3e−31 Similarity tohypothetical protein encoded by slr0318 - Synechocystis sp. q2u1v3 2e−19Predicted protein. q5axc1 6e−18 Hypothetical protein. q4w9x2 2e−16 L-PSPendoribonuclease family protein, putative. a1d9u3 1e−15 L-PSPendoribonuclease family protein, putative. a2qyq7 1e−14 Function: Mmf1pinfluences the maintenance of mitochondrial DNA. q55925 1e−12 Slr0318protein. q68e49 2e−12 Endoribonuclease L-psp family protein. a0r4686e−12 Endoribonuclease L-psp family protein. a2qti5 1e−11 ContigAn09c0050, complete genome. q5aqu2 2e−11 Hypothetical protein. a0ywm95e−11 Endoribonuclease L-PSP. q5arf7 1e−10 Hypothetical protein. q3m1g12e−10 Endoribonuclease L-PSP. q5b5q5 1e−09 Hypothetical protein. q2h8292e−09 Hypothetical protein. q2u111 2e−08 Predicted protein. a4qwk3 1e−07Hypothetical protein. q0mf29 4e−04 Hypothetical protein. q46me6 5e−04Endoribonuclease L-PSP. q8xes9 5e−04 Hypothetical transmembrane protein(Hypothetical protein). q1lgu9 6e−04 Endoribonuclease L-PSP. q0kde16e−04 Putative translation initiation inhibitor, yjgF family.

None of the hits in the homology search revealed a polypeptide that hasbeen identified as having protease activity.

Example 4 Expression of A. niger 19 kDa Protease Gene in A. oryzae

Aspergillus oryzae strain BECh-2 was inoculated to 100 ml of YPG mediumand incubated for 16 hrs at 32° C. at 80 rpm. Pellets were collected andwashed with 0.6 M KCl, and resuspended 20 ml 0.6 M KCl containing acommercial β-glucanase product (GLUCANEX™, Novozymes A/S, Bagsvrd,Denmark) at a final concentration of 600 μl per ml. The suspension wasincubated at 32° C. and 80 rpm until protoplasts were formed, and thenwashed twice with STC buffer. The protoplasts were counted with ahematometer and resuspended and adjusted in an 8:2:0.1 solution ofSTC:STPC:DMSO to a final concentration of 2.5×10⁷ protoplasts/ml.

Approximately 3 μg of pHUda772 was added to 100 μl of the protoplastsuspension, mixed gently, and incubated on ice for 20 minutes. One ml ofSPTC was added and the protoplast suspension was incubated for 30minutes at 37° C. After the addition of 10 ml of 50° C. COVE topagarose, the reaction was poured onto COVE agar plates and the plateswere incubated at 32° C. After 5 days transformants were selected fromthe COVE medium.

Four randomly selected transformants were inoculated into 100 ml of MS-9medium and cultivated at 32° C. for 1 day. Three ml of MS-9 medium wasinoculated into 100 ml of MDU-pH5 medium and cultivated at 30° C. for 3days.

The grown mycelia was resuspended with SDS sample buffer and heated at100° C. for 10 min. After centrifugation at 12,000 rpm for 10 min, thesupernatants were recovered and applied to SDS-PAGE analysis (CompactPAGE, AE7300 and pre-cast gel c-PAGEL, 12.5%, 76 mm (W)×70 mm (H) (ATTOCo.). Sample buffer, Running buffer and SDS buffer were prepared byfollowing ATTO's instruction manual. After electrophoresis, the gel wasstained by SYPRO Orange protein gel stain (Invitrogen Co.). One of the19 kDa protease expressing clones, strain 772-10, was selected forfurther experiments.

Example 5 Sample Preparation of the Expressed 19 kDa Protease

One of the selected transformants expressing A. niger 19 kDa proteaseintracellulary were grown under the conditions disclosed in example 4,mycelium was collected and lyophilized.

One gram of the lyophilized cell was grinded by a mortar and suspendedin 25 ml of 10 mM phosphate buffer, pH 6.7 containing 0.5 M NaCl. Cellfree extract was obtained by centrifugation. The cell free extract wasconcentrated to 4 ml and applied to HiLoad 26/60 Superdex 200 column (GEhealthcare) pre-equilibrated by the same buffer. The sample was elutedby the same buffer (flow rate; 2 ml/min, fraction size 4 ml/2 min/fr).The chromatogram for the gel permeation is shown in FIG. 3.

SDS-PAGE was performed in combination of Compact PAGE, AE7300 andpre-cast gel c-PAGEL, 15%, 76 mm (W)×70 mm (H) (ATTO Co.). Runningbuffer and SDS buffer were prepared by following ATTO's instructionmanual. After electrophoresis, the gel was stained by SYPRO Orangeprotein gel stain (Invitrogen Co.). (see FIG. 4)

Fractions 55, 56, 57 that containing the 19 kDa protease were pooled andused for further analysis.

Example 6 Characterization of the Expressed 19 kDa Protease

Substrate Specificity of the 19 kDa Protease

Five synthetic substrates were purchased from Peptide Institute Co.,Osaka. The substrates are Glt-AAF-MCA, Suc-LLVY-MCA, Boc-FSR-MCA,Suc(OMe)-AAPV-MCA, and Z-LLE-MCA. 25 μl of 0.04 mM substrates werepreincubated at 37° C. for 5 min. 20 μl of protease sample were mixedwith 25 μl of 400 mM phosphate buffer, pH 6.7, 5 μl of 2 M NaCl, and 25μl of Milli Q water, and then preincubated at 37° C. for 5 min. Thereactions were started by mixing the substrate solutions and the enzymesolutions. Increases of fluorescent strength were measured by FL600Microplate Fluorescence Reader with 360 nm excitation and 460 nmemission filters at 37° C. for 30 min. Suc-LLVY-MCA is the bestsubstrate.

Glt-AAF-MCA 1.6% Suc-LLVY-MCA 100.0% Boc-FSR-MCA 0.3% Suc(OMe)-AAPV-MCA0.2% Z-LLE-MCA 0.1%

Effects of Inhibitors

4-(2-aminoethyl)-benzenesulfonyl fluoride (AEBSF), leupeptin, pepstatinA, ZnSO₄, and EDTA were purchased from Wako Chemical Co., Osaka. Theinhibitors were 4.5 mg/10 ml leupeptin in DMSO diluted 10 times by MilliQ water, 3 mg/10 ml pepstatin A in DMSO diluted 10 times by Milli-Qwater, 10 mM AEBSF, 10 mM ZnSO₄, and 10 mM EDTA. The substrate was 0.04mM Suc-LLVY-MCA. Enzyme solution contains 5 μl of pooled 19 kDa proteasefraction, 10 μl of inhibitors, 25 μl of 400 mM KPB, pH6.7, and 35 μl ofMilli-Q water. The substrate solution and the enzyme solutions werepreincubated separately at 37° C. for 5 min. The activities weremeasured as described above.

residual activity (%) No inhibitor 100 Leupeptin 89 AEBSF 100 Pepstatin91 ZnSO4 99 EDTA 101

No clear inhibition by any inhibitor was observed.

pH Profile

Phosphate buffer pH6, 7, 8, and Diethanolamine buffer pH8, 9, 10 wereused. The substrate solution was 0.04 mM Suc-LLVY-MCA. The enzymesolution contains 5 μl of 19 kDa protease, 25 μl of buffer, 5 μL of 2 MNaCl and 40 μL of Milli Q water. Assay was performed as describedbefore. The results are shown in FIG. 5. The 19 kDa protease is analkaline protease with the pH optimum 8-9.

The invention described and claimed herein is not to be limited in scopeby the specific aspects herein disclosed, since these aspects areintended as illustrations of several aspects of the invention. Anyequivalent aspects are intended to be within the scope of thisinvention. Indeed, various modifications of the invention in addition tothose shown and described herein will become apparent to those skilledin the art from the foregoing description. Such modifications are alsointended to fall within the scope of the appended claims. In the case ofconflict, the present disclosure including definitions will control.

Various references are cited herein, the disclosures of which areincorporated by reference in their entireties.

1. A recombinant or isolated cell, derived from a parent cell, whereinthe parent cell comprises a protein comprising a protease having atleast 95% sequence identity to 2 to 148 of SEQ ID NO: 5, wherein therecombinant or isolated cell is produced by disrupting or deleting, inthe parent cell, the nucleotide sequence encoding the parent cellprotein, and wherein, compared to the parent cell, the recombinant orisolated cell has reduced production of the protein comprising theprotease having at least 95% sequence identity to 2 to 148 of SEQ ID NO:5.
 2. The recombinant or isolated cell of claim 1, which furthercomprises a gene encoding a heterologous protein.
 3. A recombinant cell,derived from a parent cell, wherein the parent cell comprises a proteincomprising a protease having at least 95% sequence identity to 2 to 148of SEQ ID NO: 5, wherein the recombinant cell is produced by disruptingor deleting, in the parent cell, the nucleotide sequence encoding theparent cell protein, and wherein, compared to the parent cell, therecombinant cell has reduced production of the protein comprising theprotease having at least 95% sequence identity to 2 to 148 of SEQ ID NO:5.
 4. The recombinant or isolated cell of claim 1, wherein the proteasehaving at least 95% sequence identity to 2 to 148 of SEQ ID NO: 5consists of the amino acid sequence 2 to 148 of SEQ ID NO:
 5. 5. Therecombinant or isolated cell of claim 1, wherein the protein comprisingthe protease having at least 95% sequence identity to 2 to 148 of SEQ IDNO: 5 consists of the amino acid sequence 2 to 148 of SEQ ID NO:
 5. 6.The recombinant cell of claim 3, which further comprises a gene encodinga heterologous protein.
 7. The recombinant cell of claim 3, wherein theprotease having at least 95% sequence identity to 2 to 148 of SEQ ID NO:5 consists of the amino acid sequence 2 to 148 of SEQ ID NO:
 5. 8. Therecombinant cell of claim 3, wherein the protein comprising the proteasehaving at least 95% sequence identity to 2 to 148 of SEQ ID NO: 5consists of the amino acid sequence 2 to 148 of SEQ ID NO: 5.